presenting diameter in vertex presentation

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StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

StatPearls [Internet].

Delivery, face and brow presentation.

Julija Makajeva ; Mohsina Ashraf .

Affiliations

Last Update: January 9, 2023 .

Continuing Education Activity

Face and brow presentation is a malpresentation during labor when the presenting part is either the face or, in the case of brow presentation, it is the area between the orbital ridge and the anterior fontanelle. This activity reviews the evaluation and management of these two presentations and explains the interprofessional team's role in safely managing delivery for both the mother and the baby.

Identify the mechanism of labor in the face and brow presentation.
Differentiate potential maternal and fetal complications during the face and brow presentations.
Evaluate different management approaches for the face and brow presentation.
Introduction

The term presentation describes the leading part of the fetus or the anatomical structure closest to the maternal pelvic inlet during labor. The presentation can roughly be divided into the following classifications: cephalic, breech, shoulder, and compound. Cephalic presentation is the most common and can be further subclassified as vertex, sinciput, brow, face, and chin. The most common presentation in term labor is the vertex, where the fetal neck is flexed to the chin, minimizing the head circumference. Face presentation is an abnormal form of cephalic presentation where the presenting part is the mentum. This typically occurs because of hyperextension of the neck and the occiput touching the fetal back. Incidence of face presentation is rare, accounting for approximately 1 in 600 of all presentations. [1] [2] [3] In brow presentation, the neck is not extended as much as in face presentation, and the leading part is the area between the anterior fontanelle and the orbital ridges. Brow presentation is considered the rarest of all malpresentation, with a prevalence of 1 in 500 to 1 in 4000 deliveries. [3]

Both face and brow presentations occur due to extension of the fetal neck instead of flexion; therefore, conditions that would lead to hyperextension or prevent flexion of the fetal neck can all contribute to face or brow presentation. These risk factors may be related to either the mother or the fetus. Maternal risk factors are preterm delivery, contracted maternal pelvis, platypelloid pelvis, multiparity, previous cesarean section, and black race. Fetal risk factors include anencephaly, multiple loops of cord around the neck, masses of the neck, macrosomia, and polyhydramnios. [2] [4] [5] These malpresentations are usually diagnosed during the second stage of labor when performing a digital examination. Palpating orbital ridges, nose, malar eminences, mentum, mouth, gums, and chin in face presentation is possible. Based on the position of the chin, face presentation can be further divided into mentum anterior, posterior, or transverse. In brow presentation, the anterior fontanelle and face can be palpated except for the mouth and the chin. Brow presentation can then be further described based on the position of the anterior fontanelle as frontal anterior, posterior, or transverse. Diagnosing the exact presentation can be challenging, and face presentation may be misdiagnosed as frank breech. To avoid any confusion, a bedside ultrasound scan can be performed. [6] Ultrasound imaging can show a reduced angle between the occiput and the spine or the chin is separated from the chest. However, ultrasound does not provide much predictive value for the outcome of labor. [7]

Anatomy and Physiology

Before discussing the mechanism of labor in the face or brow presentation, it is crucial to highlight some anatomical landmarks and their measurements.

Planes and Diameters of the Pelvis

The 3 most important planes in the female pelvis are the pelvic inlet, mid-pelvis, and pelvic outlet. Four diameters can describe the pelvic inlet: anteroposterior, transverse, and 2 obliques. Furthermore, based on the landmarks on the pelvic inlet, there are 3 different anteroposterior diameters named conjugates: true conjugate, obstetrical conjugate, and diagonal conjugate. Only the latter can be measured directly during the obstetric examination. The shortest of these 3 diameters is obstetrical conjugate, which measures approximately 10.5 cm and is the distance between the sacral promontory and 1 cm below the upper border of the symphysis pubis. This measurement is clinically significant as the fetal head must pass through this diameter during the engagement phase. The transverse diameter measures about 13.5 cm and is the widest distance between the innominate line on both sides. The shortest distance in the mid pelvis is the interspinous diameter and usually is only about 10 cm.

Fetal Skull Diameters

There are 6 distinguished longitudinal fetal skull diameters:

Suboccipito-bregmatic: from the center of anterior fontanelle (bregma) to the occipital protuberance, measuring 9.5 cm. This is the diameter presented in the vertex presentation.
Suboccipito-frontal: from the anterior part of bregma to the occipital protuberance, measuring 10 cm
Occipito-frontal: from the root of the nose to the most prominent part of the occiput, measuring 11.5 cm
Submento-bregmatic: from the center of the bregma to the angle of the mandible, measuring 9.5 cm. This is the diameter in the face presentation where the neck is hyperextended.
Submento-vertical: from the midpoint between fontanelles and the angle of the mandible, measuring 11.5 cm
Occipito-mental: from the midpoint between fontanelles and the tip of the chin, measuring 13.5 cm. It is the presenting diameter in brow presentation.

Cardinal Movements of Normal Labor

Neck flexion
Internal rotation
Extension (delivers head)
External rotation (restitution)
Expulsion (delivery of anterior and posterior shoulders)

Some key movements are impossible in the face or brow presentations. Based on the information provided above, it is obvious that labor be arrested in brow presentation unless it spontaneously changes to the face or vertex, as the occipito-mental diameter of the fetal head is significantly wider than the smallest diameter of the female pelvis. Face presentation can, however, be delivered vaginally, and further mechanisms of face delivery are explained in later sections.

Indications

As mentioned previously, spontaneous vaginal delivery can be successful in face presentation. However, the main indication for vaginal delivery in such circumstances would be a maternal choice. It is crucial to have a thorough conversation with a mother, explaining the risks and benefits of vaginal delivery with face presentation and a cesarean section. Informed consent and creating a rapport with the mother is an essential aspect of safe and successful labor.

Contraindications

Vaginal delivery of face presentation is contraindicated if the mentum is lying posteriorly or is in a transverse position. In such a scenario, the fetal brow is pressing against the maternal symphysis pubis, and the short fetal neck, which is already maximally extended, cannot span the surface of the maternal sacrum. In this position, the diameter of the head is larger than the maternal pelvis, and it cannot descend through the birth canal. Therefore, the cesarean section is recommended as the safest mode of delivery for mentum posterior face presentations. Attempts to manually convert face presentation to vertex, manual or forceps rotation of the persistent posterior chin to anterior are contraindicated as they can be dangerous. Persistent brow presentation itself is a contraindication for vaginal delivery unless the fetus is significantly small or the maternal pelvis is large.

Continuous electronic fetal heart rate monitoring is recommended for face and brow presentations, as heart rate abnormalities are common in these scenarios. One study found that only 14% of the cases with face presentation had no abnormal traces on the cardiotocograph. [8] External transducer devices are advised to prevent damage to the eyes. When internal monitoring is inevitable, monitoring devices on bony parts should be placed carefully.

Consultations that are typically requested for patients with delivery of face/brow presentation include the following:

Experienced midwife, preferably looking after laboring women 1:1
Senior obstetrician
Neonatal team - in case of need for resuscitation
Anesthetic team - to provide necessary pain control (eg, epidural)
Theatre team - in case of failure to progress, an emergency cesarean section is required.
Preparation

No specific preparation is required for face or brow presentation. However, discussing the labor options with the mother and birthing partner and informing members of the neonatal, anesthetic, and theatre co-ordinating teams is essential.

Technique or Treatment

Mechanism of Labor in Face Presentation

During contractions, the pressure exerted by the fundus of the uterus on the fetus and the pressure of the amniotic fluid initiate descent. During this descent, the fetal neck extends instead of flexing. The internal rotation determines the outcome of delivery. If the fetal chin rotates posteriorly, vaginal delivery would not be possible, and cesarean section is permitted. The approach towards mentum-posterior delivery should be individualized, as the cases are rare. Expectant management is acceptable in multiparous women with small fetuses, as a spontaneous mentum-anterior rotation can occur. However, there should be a low threshold for cesarean section in primigravida women or women with large fetuses.

The pubis is described as mentum-anterior when the fetal chin is rotated towards the maternal symphysis. In these cases, further descent through the vaginal canal continues, with approximately 73% of cases delivering spontaneously. [9] The fetal mentum presses on the maternal symphysis pubis, and the head is delivered by flexion. The occiput is pointing towards the maternal back, and external rotation happens. Shoulders are delivered in the same manner as in vertex delivery.

Mechanism of Labor in Brow Presentation

As this presentation is considered unstable, it is usually converted into a face or an occiput presentation. Due to the cephalic diameter being wider than the maternal pelvis, the fetal head cannot engage; thus, brow delivery cannot occur. Unless the fetus is small or the pelvis is very wide, the prognosis for vaginal delivery is poor. With persistent brow presentation, a cesarean section is required for safe delivery.

Complications

As the cesarean section is becoming a more accessible mode of delivery in malpresentations, the incidence of maternal and fetal morbidity and mortality during face presentation has dropped significantly. [10] However, some complications are still associated with the nature of labor in face presentation. Due to the fetal head position, it is more challenging for the head to engage in the birth canal and descend, resulting in prolonged labor. Prolonged labor itself can provoke fetal distress and arrhythmias. If the labor arrests or signs of fetal distress appear on CTG, the recommended next step in management is an emergency cesarean section, which in itself carries a myriad of operative and post-operative complications. Finally, due to the nature of the fetal position and prolonged duration of labor in face presentation, neonates develop significant edema of the skull and face. Swelling of the fetal airway may also be present, resulting in respiratory distress after birth and possible intubation.

Clinical Significance

During vertex presentation, the fetal head flexes, bringing the chin to the chest, forming the smallest possible fetal head diameter, measuring approximately 9.5 cm. With face and brow presentation, the neck hyperextends, resulting in greater cephalic diameters. As a result, the fetal head engages later, and labor progresses more slowly. Failure to progress in labor is also more common in both presentations compared to the vertex presentation. Furthermore, when the fetal chin is in a posterior position, this prevents further flexion of the fetal neck, as browns are pressing on the symphysis pubis. As a result, descending through the birth canal is impossible. Such presentation is considered undeliverable vaginally and requires an emergency cesarean section. Manual attempts to change face presentation to vertex or manual or forceps rotation to mentum anterior are considered dangerous and discouraged.

Enhancing Healthcare Team Outcomes

A multidisciplinary team of healthcare experts supports the woman and her child during labor and the perinatal period. For a face or brow presentation to be appropriately diagnosed, an experienced midwife and obstetrician must be involved in the vaginal examination and labor monitoring. As fetal anomalies, such as anencephaly or goiter, can contribute to face presentation, sonographers experienced in antenatal scanning should also be involved in the care. It is advised to inform the anesthetic and neonatal teams in advance of the possible need for emergency cesarean section and resuscitation of the neonate. [11] [12]

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Disclosure: Julija Makajeva declares no relevant financial relationships with ineligible companies.

Disclosure: Mohsina Ashraf declares no relevant financial relationships with ineligible companies.

This book is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ), which permits others to distribute the work, provided that the article is not altered or used commercially. You are not required to obtain permission to distribute this article, provided that you credit the author and journal.

Cite this Page Makajeva J, Ashraf M. Delivery, Face and Brow Presentation. [Updated 2023 Jan 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

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Face and Brow Presentation

Author: Teresa Marino, MD; Chief Editor: Carl V Smith, MD more...
Sections Face and Brow Presentation
Mechanism of Labor
Labor Management

At the onset of labor, assessment of the fetal presentation with respect to the maternal birth canal is critical to the route of delivery. At term, the vast majority of fetuses present in the vertex presentation, where the fetal head is flexed so that the chin is in contact with the fetal thorax. The fetal spine typically lies along the longitudinal axis of the uterus. Nonvertex presentations (including breech, transverse lie, face, brow, and compound presentations) occur in less than 4% of fetuses at term. Malpresentation of the vertex presentation occurs if there is deflexion or extension of the fetal head leading to brow or face presentation, respectively.

In a face presentation, the fetal head and neck are hyperextended, causing the occiput to come in contact with the upper back of the fetus while lying in a longitudinal axis. The presenting portion of the fetus is the fetal face between the orbital ridges and the chin. The fetal chin (mentum) is the point designated for reference during an internal examination through the cervix. The occiput of a vertex is usually hard and has a smooth contour, while the face and brow tend to be more irregular and soft. Like the occiput, the mentum can present in any position relative to the maternal pelvis. For example, if the mentum presents in the left anterior quadrant of the maternal pelvis, it is designated as left mentum anterior (LMA).

In a brow presentation, the fetal head is midway between full flexion (vertex) and hyperextension (face) along a longitudinal axis. The presenting portion of the fetal head is between the orbital ridge and the anterior fontanel. The face and chin are not included. The frontal bones are the point of designation and can present (as with the occiput during a vertex delivery) in any position relative to the maternal pelvis. When the sagittal suture is transverse to the pelvic axis and the anterior fontanel is on the right maternal side, the fetus would be in the right frontotransverse position (RFT).

Face presentation occurs in 1 of every 600-800 live births, averaging about 0.2% of live births. Causative factors associated with a face presentation are similar to those leading to general malpresentation and those that prevent head flexion or favor extension. Possible etiology includes multiple gestations, grand multiparity, fetal malformations, prematurity, and cephalopelvic disproportion. At least one etiological factor may be identified in up to 90% of cases with face presentation.

Fetal anomalies such as hydrocephalus, anencephaly, and neck masses are common risk factors and may account for as many as 60% of cases of face presentation. For example, anencephaly is found in more than 30% of cases of face presentation. Fetal thyromegaly and neck masses also lead to extension of the fetal head.

A contracted pelvis or cephalopelvic disproportion, from either a small pelvis or a large fetus, occurs in 10-40% of cases. Multiparity or a large abdomen can cause decreased uterine tone, leading to natural extension of the fetal head.

Face presentation is diagnosed late in the first or second stage of labor by examination of a dilated cervix. On digital examination, the distinctive facial features of the nose, mouth, and chin, the malar bones, and particularly the orbital ridges can be palpated. This presentation can be confused with a breech presentation because the mouth may be confused with the anus and the malar bones or orbital ridges may be confused with the ischial tuberosities. The facial presentation has a triangular configuration of the mouth to the orbital ridges compared to the breech presentation of the anus and fetal genitalia. During Leopold maneuvers, diagnosis is very unlikely. Diagnosis can be confirmed by ultrasound evaluation, which reveals a hyperextended fetal neck. [ 1 , 2 ]

Brow presentation is the least common of all fetal presentations and the incidence varies from 1 in 500 deliveries to 1 in 1400 deliveries. Brow presentation may be encountered early in labor but is usually a transitional state and converts to a vertex presentation after the fetal neck flexes. Occasionally, further extension may occur resulting in a face presentation.

The causes of a persistent brow presentation are generally similar to those causing a face presentation and include cephalopelvic disproportion or pelvic contracture, increasing parity and prematurity. These are implicated in more than 60% of cases of persistent brow presentation. Premature rupture of membranes may precede brow presentation in as many as 27% of cases.

Diagnosis of a brow presentation can occasionally be made with abdominal palpation by Leopold maneuvers. A prominent occipital prominence is encountered along the fetal back, and the fetal chin is also palpable; however, the diagnosis of a brow presentation is usually confirmed by examination of a dilated cervix. The orbital ridge, eyes, nose, forehead, and anterior fontanelle are palpated. The mouth and chin are not palpable, thus excluding face presentation. Fetal ultrasound evaluation again notes a hyperextended neck.

As with face presentation, diagnosis is often made late in labor with half of cases occurring in the second stage of labor. The most common position is the mentum anterior, which occurs about twice as often as either transverse or posterior positions. A higher cesarean delivery rate occurs with a mentum transverse or posterior [ 3 ] position than with a mentum anterior position.

The mechanism of labor consists of the cardinal movements of engagement, descent, flexion, internal rotation, and the accessory movements of extension and external rotation. Intuitively, the cardinal movements of labor for a face presentation are not completely identical to those of a vertex presentation.

While descending into the pelvis, the natural contractile forces combined with the maternal pelvic architecture allow the fetal head to either flex or extend. In the vertex presentation, the vertex is flexed such that the chin rests on the fetal chest, allowing the suboccipitobregmatic diameter of approximately 9.5 cm to be the widest diameter through the maternal pelvis. This is the smallest of the diameters to negotiate the maternal pelvis. Following engagement in the face presentation, descent is made. The widest diameter of the fetal head negotiating the pelvis is the trachelobregmatic or submentobregmatic diameter, which is 10.2 cm (0.7 cm larger than the suboccipitobregmatic diameter). Because of this increased diameter, engagement does not occur until the face is at +2 station.

Fetuses with face presentation may initially begin labor in the brow position. Using x-ray pelvimetry in a series of 7 patients, Borrell and Ferstrom demonstrated that internal rotation occurs between the ischial spines and the ischial tuberosities, making the chin the presenting part, lower than in the vertex presentation. [ 4 , 5 ] Following internal rotation, the mentum is below the maternal symphysis, and delivery occurs by flexion of the fetal neck. As the face descends onto the perineum, the anterior fetal chin passes under the symphysis and flexion of the head occurs, making delivery possible with maternal expulsive forces.

The above mechanisms of labor in the term infant can occur only if the mentum is anterior and at term, only the mentum anterior face presentation is likely to deliver vaginally. If the mentum is posterior or transverse, the fetal neck is too short to span the length of the maternal sacrum and is already at the point of maximal extension. The head cannot deliver as it cannot extend any further through the symphysis and cesarean delivery is the safest route of delivery.

Fortunately, the mentum is anterior in over 60% of cases of face presentation, transverse in 10-12% of cases, and posterior only 20-25% of the time. Fetuses with the mentum transverse position usually rotate to the mentum anterior position, and 25-33% of fetuses with mentum posterior position rotate to a mentum anterior position. When the mentum is posterior, the neck, head and shoulders must enter the pelvis simultaneously, resulting in a diameter too large for the maternal pelvis to accommodate unless in the very preterm or small infant.

Three labor courses are possible when the fetal head engages in a brow presentation. The brow may convert to a vertex presentation, to a face presentation, or remain as a persistent brow presentation. More than 50% of brow presentations will convert to vertex or face presentation and labor courses are managed accordingly when spontaneous conversion occurs.

In the brow presentation, the occipitomental diameter, which is the largest diameter of the fetal head, is the presenting portion. Descent and internal rotation occur only with an adequate pelvis and if the face can fit under the pubic arch. While the head descends, it becomes wedged into the hollow of the sacrum. Downward pressure from uterine contractions and maternal expulsive forces may cause the mentum to extend anteriorly and low to present at the perineum as a mentum anterior face presentation.

If internal rotation does not occur, the occipitomental diameter, which measures 1.5 cm wider than the suboccipitobregmatic diameter and is thus the largest diameter of the fetal head, presents at the pelvic inlet. The head may engage but can descend only with significant molding. This molding and subsequent caput succedaneum over the forehead can become so extensive that identification of the brow by palpation is impossible late in labor. This may result in a missed diagnosis in a patient who presents later in active labor.

If the mentum is anterior and the forces of labor are directed toward the fetal occiput, flexing the head and pivoting the face under the pubic arch, there is conversion to a vertex occiput posterior position. If the occiput lies against the sacrum and the forces of labor are directed against the fetal mentum, the neck may extend further, leading to a face presentation.

The persistent brow presentation with subsequent delivery only occurs in cases of a large pelvis and/or a small infant. Women with gynecoid pelvis or multiparity may be given the option to labor; however, dysfunctional labor and cephalopelvic disproportion are more likely if this presentation persists.

Labor management of face and brow presentation requires close observation of labor progression because cephalopelvic disproportion, dysfunctional labor, and prolonged labor are much more common. As mentioned above, the trachelobregmatic or submentobregmatic diameters are larger than the suboccipitobregmatic diameter. Duration of labor with a face presentation is generally the same as duration of labor with a vertex presentation, although a prolonged labor may occur. As long as maternal or fetal compromise is not evident, labor with a face presentation may continue. [ 6 ] A persistent mentum posterior presentation is an indication for delivery by cesarean section.

Continuous electronic fetal heart rate monitoring is considered mandatory by many authors because of the increased incidence of abnormal fetal heart rate patterns and/or nonreassuring fetal heart rate patterns. [ 7 ] An internal fetal scalp electrode may be used, but very careful application of the electrode must be ensured. The mentum is the recommended site of application. Facial edema is common and can obscure the fetal facial anatomy and improper placement can lead to facial and ophthalmic injuries. Oxytocin can be used to augment labor using the same precautions as in a vertex presentation and the same criteria of assessment of uterine activity, adequacy of the pelvis, and reassuring fetal heart tracing.

Fetuses with face presentation can be delivered vaginally with overall success rates of 60-70%, while more than 20% of fetuses with face presentation require cesarean delivery. Cesarean delivery is performed for the usual obstetrical indications, including arrest of labor and nonreassuring fetal heart rate pattern.

Attempts to manually convert the face to vertex (Thom maneuver) or to rotate a posterior position to a more favorable anterior mentum position are rarely successful and are associated with high fetal morbidity and mortality and maternal morbidity, including cord prolapse, uterine rupture, and fetal cervical spine injury with neurological impairment. Given the availability and safety of cesarean delivery, internal rotation maneuvers are no longer justified unless cesarean section cannot be readily performed.

Internal podalic version and breech extraction are also no longer recommended in the modern management of the face presentation. [ 8 ]

Operative delivery with forceps must be approached with caution. Since engagement occurs when the face is at +2 position, forceps should only be applied to the face that has caused the perineum to bulge. Increased complications to both mother and fetus can occur [ 9 ] and operative delivery must be approached with caution or reserved when cesarean section is not readily available. Forceps may be used if the mentum is anterior. Although the landmarks are different, the application of any forceps is made as if the fetus were presenting directly in the occiput anterior position. The mouth substitutes for the posterior fontanelle, and the mentum substitutes for the occiput. Traction should be downward to maintain extension until the mentum passes under the symphysis, and then gradually elevated to allow the head to deliver by flexion. During delivery, hyperextension of the fetal head should be avoided.

As previously mentioned, the persistent brow presentation has a poor prognosis for vaginal delivery unless the fetus is small, premature, or the maternal pelvis is large. Expectant management is reasonable if labor is progressing well and the fetal well-being is assessed, as there can be spontaneous conversion to face or vertex presentation. The earlier in labor that brow presentation is diagnosed, the higher the likelihood of conversion. Minimal intervention during labor is recommended and some feel the use of oxytocin in the brow presentation is contraindicated.

The use of operative vaginal delivery or manual conversion of a brow to a more favorable presentation is contraindicated as the risks of perinatal morbidity and mortality are unacceptably high. Prolonged, dysfunctional, and arrest of labor are common, necessitating cesarean section delivery.

The incidence of perinatal morbidity and mortality and maternal morbidity has decreased due to the increased incidence of cesarean section delivery for malpresentation, including face and brow presentation.

Neonates delivered in the face presentation exhibit significant facial and skull edema, which usually resolves within 24-48 hours. Trauma during labor may cause tracheal and laryngeal edema immediately after delivery, which can result in neonatal respiratory distress. In addition, fetal anomalies or tumors, such as fetal goiters that may have contributed to fetal malpresentation, may make intubation difficult. Physicians with expertise in neonatal resuscitation should be present at delivery in the event that intubation is required. When a fetal anomaly has been previously diagnosed by ultrasonographic evaluation, the appropriate pediatric specialists should be consulted and informed at time of labor.

Bellussi F, Ghi T, Youssef A, et al. The use of intrapartum ultrasound to diagnose malpositions and cephalic malpresentations. Am J Obstet Gynecol . 2017 Dec. 217 (6):633-41. [QxMD MEDLINE Link] .

[Guideline] Ghi T, Eggebø T, Lees C, et al. ISUOG Practice Guidelines: intrapartum ultrasound. Ultrasound Obstet Gynecol . 2018 Jul. 52 (1):128-39. [QxMD MEDLINE Link] . [Full Text] .

Shaffer BL, Cheng YW, Vargas JE, Laros RK Jr, Caughey AB. Face presentation: predictors and delivery route. Am J Obstet Gynecol . 2006 May. 194(5):e10-2. [QxMD MEDLINE Link] .

Borell U, Fernstrom I. The mechanism of labour. Radiol Clin North Am . 1967 Apr. 5(1):73-85. [QxMD MEDLINE Link] .

Borell U, Fernstrom I. The mechanism of labour in face and brow presentation: a radiographic study. Acta Obstet Gynecol Scand . 1960. 39:626-44.

Gardberg M, Leonova Y, Laakkonen E. Malpresentations--impact on mode of delivery. Acta Obstet Gynecol Scand . 2011 May. 90(5):540-2. [QxMD MEDLINE Link] .

Collaris RJ, Oei SG. External cephalic version: a safe procedure? A systematic review of version-related risks. Acta Obstet Gynecol Scand . 2004 Jun. 83(6):511-8. [QxMD MEDLINE Link] .

Verspyck E, Bisson V, Gromez A, Resch B, Diguet A, Marpeau L. Prophylactic attempt at manual rotation in brow presentation at full dilatation. Acta Obstet Gynecol Scand . 2012 Nov. 91(11):1342-5. [QxMD MEDLINE Link] .

Johnson JH, Figueroa R, Garry D. Immediate maternal and neonatal effects of forceps and vacuum-assisted deliveries. Obstet Gynecol . 2004 Mar. 103(3):513-8. [QxMD MEDLINE Link] .

Benedetti TJ, Lowensohn RI, Truscott AM. Face presentation at term. Obstet Gynecol . 1980 Feb. 55(2):199-202. [QxMD MEDLINE Link] .

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Contributor Information and Disclosures

Teresa Marino, MD Assistant Professor, Attending Physician, Division of Maternal-Fetal Medicine, Tufts Medical Center Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference Disclosure: Received salary from Medscape for employment. for: Medscape.

Carl V Smith, MD The Distinguished Chris J and Marie A Olson Chair of Obstetrics and Gynecology, Professor, Department of Obstetrics and Gynecology, Senior Associate Dean for Clinical Affairs, University of Nebraska Medical Center Carl V Smith, MD is a member of the following medical societies: American College of Obstetricians and Gynecologists , American Institute of Ultrasound in Medicine , Association of Professors of Gynecology and Obstetrics , Central Association of Obstetricians and Gynecologists , Society for Maternal-Fetal Medicine , Council of University Chairs of Obstetrics and Gynecology , Nebraska Medical Association Disclosure: Nothing to disclose.

Chitra M Iyer, MD, Perinatologist, Obstetrix Medical Group, Fort Worth, Texas.

Chitra M Iyer, MD is a member of the following medical societies: American College of Obstetricians and Gynecologists , Society of Maternal-Fetal Medicine .

Disclosure: Nothing to disclose.

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Fetal Presentation, Position, and Lie (Including Breech Presentation)

Variations in Fetal Position and Presentation |

During pregnancy, the fetus can be positioned in many different ways inside the mother's uterus. The fetus may be head up or down or facing the mother's back or front. At first, the fetus can move around easily or shift position as the mother moves. Toward the end of the pregnancy the fetus is larger, has less room to move, and stays in one position. How the fetus is positioned has an important effect on delivery and, for certain positions, a cesarean delivery is necessary. There are medical terms that describe precisely how the fetus is positioned, and identifying the fetal position helps doctors to anticipate potential difficulties during labor and delivery.

Presentation refers to the part of the fetus’s body that leads the way out through the birth canal (called the presenting part). Usually, the head leads the way, but sometimes the buttocks (breech presentation), shoulder, or face leads the way.

Position refers to whether the fetus is facing backward (occiput anterior) or forward (occiput posterior). The occiput is a bone at the back of the baby's head. Therefore, facing backward is called occiput anterior (facing the mother’s back and facing down when the mother lies on her back). Facing forward is called occiput posterior (facing toward the mother's pubic bone and facing up when the mother lies on her back).

Lie refers to the angle of the fetus in relation to the mother and the uterus. Up-and-down (with the baby's spine parallel to mother's spine, called longitudinal) is normal, but sometimes the lie is sideways (transverse) or at an angle (oblique).

For these aspects of fetal positioning, the combination that is the most common, safest, and easiest for the mother to deliver is the following:

Head first (called vertex or cephalic presentation)

Facing backward (occiput anterior position)

Spine parallel to mother's spine (longitudinal lie)

Neck bent forward with chin tucked

Arms folded across the chest

If the fetus is in a different position, lie, or presentation, labor may be more difficult, and a normal vaginal delivery may not be possible.

Variations in fetal presentation, position, or lie may occur when

The fetus is too large for the mother's pelvis (fetopelvic disproportion).

The uterus is abnormally shaped or contains growths such as fibroids .

The fetus has a birth defect .

There is more than one fetus (multiple gestation).

presenting diameter in vertex presentation

Position and Presentation of the Fetus

Toward the end of pregnancy, the fetus moves into position for delivery. Normally, the presentation is vertex (head first), and the position is occiput anterior (facing toward the pregnant person's spine) and with the face and body angled to one side and the neck flexed.

Variations in fetal presentations include face, brow, breech, and shoulder. Occiput posterior position (facing forward, toward the mother's pubic bone) is less common than occiput anterior position (facing backward, toward the mother's spine).

Variations in Fetal Position and Presentation

Some variations in position and presentation that make delivery difficult occur frequently.

Occiput posterior position

In occiput posterior position (sometimes called sunny-side up), the fetus is head first (vertex presentation) but is facing forward (toward the mother's pubic bone—that is, facing up when the mother lies on her back). This is a very common position that is not abnormal, but it makes delivery more difficult than when the fetus is in the occiput anterior position (facing toward the mother's spine—that is facing down when the mother lies on her back).

When a fetus faces up, the neck is often straightened rather than bent,which requires more room for the head to pass through the birth canal. Delivery assisted by a vacuum device or forceps or cesarean delivery may be necessary.

Breech presentation

In breech presentation, the baby's buttocks or sometimes the feet are positioned to deliver first (before the head).

When delivered vaginally, babies that present buttocks first are more at risk of injury or even death than those that present head first.

The reason for the risks to babies in breech presentation is that the baby's hips and buttocks are not as wide as the head. Therefore, when the hips and buttocks pass through the cervix first, the passageway may not be wide enough for the head to pass through. In addition, when the head follows the buttocks, the neck may be bent slightly backwards. The neck being bent backward increases the width required for delivery as compared to when the head is angled forward with the chin tucked, which is the position that is easiest for delivery. Thus, the baby’s body may be delivered and then the head may get caught and not be able to pass through the birth canal. When the baby’s head is caught, this puts pressure on the umbilical cord in the birth canal, so that very little oxygen can reach the baby. Brain damage due to lack of oxygen is more common among breech babies than among those presenting head first.

In a first delivery, these problems may occur more frequently because a woman’s tissues have not been stretched by previous deliveries. Because of risk of injury or even death to the baby, cesarean delivery is preferred when the fetus is in breech presentation, unless the doctor is very experienced with and skilled at delivering breech babies or there is not an adequate facility or equipment to safely perform a cesarean delivery.

Breech presentation is more likely to occur in the following circumstances:

Labor starts too soon (preterm labor).

The uterus is abnormally shaped or contains abnormal growths such as fibroids .

Mechanism of Labour

First Online: 02 August 2023

Cite this chapter

Vinayachandran S. 2 , 3 &
Sajala Vimalraj 2

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Labour and delivery, the process by which the mature foetus is expelled from the uterus, is not a passive process. It involves a complex interaction of uterine activity, the foetus and the maternal pelvis, to achieve a successful negotiation of this start of the human life. This chapter describes the Mechanism of Labour - the positional changes in the presenting part of the foetus to achieve a successful passage through the birth canal - with a brief look at the passenger (the foetus), the passage (the pelvis) and the powers (the uterine activity) and the complex interaction between them, resulting in the six cardinal movements – descent, flexion, internal rotation, extension, restitution and external rotation. It also gives an overview of the normal progression of Labour and the evolution from the traditional model described by Friedman to the contemporary partogram, influenced by the pioneering work of Zhang et al, according to which more time can be given to the labouring woman to achieve natural childbirth, provide maternal and foetal condition remains good. All of this has been incorporated into the WHO Labour Care Guide, designed to encourage Respectable Maternity Care. Intrapartum USG can also help guide the Obstetrician about the progress of Labour and the need for Caesarean Delivery

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S., V., Vimalraj, S. (2023). Mechanism of Labour. In: Garg, R. (eds) Labour and Delivery. Springer, Singapore. https://doi.org/10.1007/978-981-19-6145-8_2

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1 Vilnius University, Lithuania, Imperial London Healthcare NHS Trust
2 University of Health Sciences, Rawalpindi Medical College
PMID: 33620804
Bookshelf ID: NBK567727

The term presentation describes the leading part of the fetus or the anatomical structure closest to the maternal pelvic inlet during labor. The presentation can roughly be divided into the following classifications: cephalic, breech, shoulder, and compound. Cephalic presentation is the most common and can be further subclassified as vertex, sinciput, brow, face, and chin. The most common presentation in term labor is the vertex, where the fetal neck is flexed to the chin, minimizing the head circumference. Face presentation is an abnormal form of cephalic presentation where the presenting part is the mentum. This typically occurs because of hyperextension of the neck and the occiput touching the fetal back. Incidence of face presentation is rare, accounting for approximately 1 in 600 of all presentations. In brow presentation, the neck is not extended as much as in face presentation, and the leading part is the area between the anterior fontanelle and the orbital ridges. Brow presentation is considered the rarest of all malpresentation, with a prevalence of 1 in 500 to 1 in 4000 deliveries.

Both face and brow presentations occur due to extension of the fetal neck instead of flexion; therefore, conditions that would lead to hyperextension or prevent flexion of the fetal neck can all contribute to face or brow presentation. These risk factors may be related to either the mother or the fetus. Maternal risk factors are preterm delivery, contracted maternal pelvis, platypelloid pelvis, multiparity, previous cesarean section, and black race. Fetal risk factors include anencephaly, multiple loops of cord around the neck, masses of the neck, macrosomia, and polyhydramnios. These malpresentations are usually diagnosed during the second stage of labor when performing a digital examination. Palpating orbital ridges, nose, malar eminences, mentum, mouth, gums, and chin in face presentation is possible. Based on the position of the chin, face presentation can be further divided into mentum anterior, posterior, or transverse. In brow presentation, the anterior fontanelle and face can be palpated except for the mouth and the chin. Brow presentation can then be further described based on the position of the anterior fontanelle as frontal anterior, posterior, or transverse. Diagnosing the exact presentation can be challenging, and face presentation may be misdiagnosed as frank breech. To avoid any confusion, a bedside ultrasound scan can be performed. Ultrasound imaging can show a reduced angle between the occiput and the spine or the chin is separated from the chest. However, ultrasound does not provide much predictive value for the outcome of labor.

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Disclosure: Julija Makajeva declares no relevant financial relationships with ineligible companies.

Disclosure: Mohsina Ashraf declares no relevant financial relationships with ineligible companies.

Continuing Education Activity
Introduction
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Indications
Contraindications
Preparation
Technique or Treatment
Complications
Clinical Significance
Enhancing Healthcare Team Outcomes
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Delivery, Face and Brow Presentation

Introduction.

Anatomy and Physiology

Before discussing the mechanism of labor in the face or brow presentation, it is crucial to highlight some anatomical landmarks and their measurements.

Planes and Diameters of the Pelvis

Fetal Skull Diameters

There are 6 distinguished longitudinal fetal skull diameters:

Suboccipito-bregmatic: from the center of anterior fontanelle (bregma) to the occipital protuberance, measuring 9.5 cm. This is the diameter presented in the vertex presentation.
Suboccipito-frontal: from the anterior part of bregma to the occipital protuberance, measuring 10 cm
Occipito-frontal: from the root of the nose to the most prominent part of the occiput, measuring 11.5 cm
Submento-bregmatic: from the center of the bregma to the angle of the mandible, measuring 9.5 cm. This is the diameter in the face presentation where the neck is hyperextended.
Submento-vertical: from the midpoint between fontanelles and the angle of the mandible, measuring 11.5 cm
Occipito-mental: from the midpoint between fontanelles and the tip of the chin, measuring 13.5 cm. It is the presenting diameter in brow presentation.

Cardinal Movements of Normal Labor

Neck flexion
Internal rotation
Extension (delivers head)
External rotation (restitution)
Expulsion (delivery of anterior and posterior shoulders)

Indications

Contraindications

Consultations that are typically requested for patients with delivery of face/brow presentation include the following:

Experienced midwife, preferably looking after laboring women 1:1
Senior obstetrician
Neonatal team - in case of need for resuscitation
Anesthetic team - to provide necessary pain control (eg, epidural)
Theatre team - in case of failure to progress, an emergency cesarean section is required.

Preparation

Technique or Treatment

Mechanism of Labor in Face Presentation

Mechanism of Labor in Brow Presentation

Complications

Clinical Significance

Enhancing Healthcare Team Outcomes

Gardberg M, Leonova Y, Laakkonen E. Malpresentations--impact on mode of delivery. Acta obstetricia et gynecologica Scandinavica. 2011 May:90(5):540-2. doi: 10.1111/j.1600-0412.2011.01105.x. Epub [PubMed PMID: 21501123]

Tapisiz OL, Aytan H, Altinbas SK, Arman F, Tuncay G, Besli M, Mollamahmutoglu L, Danışman N. Face presentation at term: a forgotten issue. The journal of obstetrics and gynaecology research. 2014 Jun:40(6):1573-7. doi: 10.1111/jog.12369. Epub [PubMed PMID: 24888918]

Zayed F, Amarin Z, Obeidat B, Obeidat N, Alchalabi H, Lataifeh I. Face and brow presentation in northern Jordan, over a decade of experience. Archives of gynecology and obstetrics. 2008 Nov:278(5):427-30. doi: 10.1007/s00404-008-0600-0. Epub 2008 Feb 19 [PubMed PMID: 18283473]

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Ghi T, Eggebø T, Lees C, Kalache K, Rozenberg P, Youssef A, Salomon LJ, Tutschek B. ISUOG Practice Guidelines: intrapartum ultrasound. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 2018 Jul:52(1):128-139. doi: 10.1002/uog.19072. Epub [PubMed PMID: 29974596]

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. Intrapartum care for healthy women and babies. 2022 Dec 14:(): [PubMed PMID: 32212591]

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Fetal Malpresentation and Malposition

Fetal presentation describes which part of the fetus will enter through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy first, while position is the orientation Orientation Awareness of oneself in relation to time, place and person. Psychiatric Assessment of the fetus compared to the maternal bony pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy . Presentations include vertex (the fetal occiput will present through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy first), face, brow, shoulder, and breech. If a fetal limb is presenting next to the presenting part (e.g., the hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand: Anatomy is next to the head), this is known as a compound presentation. Malpresentation refers to any presentation other than vertex, with the most common being breech presentations. Vaginal delivery of a breech infant increases the risk for head entrapment and hypoxia Hypoxia Sub-optimal oxygen levels in the ambient air of living organisms. Ischemic Cell Damage , so, especially in the United States, mothers are generally offered a procedure to help manually rotate the baby to a head-down position instead (known as an external cephalic version) or a planned cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery .

Last updated: Feb 14, 2023

Fetal Lie and Presentation

Presenting diameter, management of cephalic and compound presentations, risks and management of breech and transverse presentations.

Share this concept:

The “presenting part” refers to the part of the baby that will come through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy first.
The position refers to how that body part (and thus the baby) is oriented within the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy .
The uterine fundus Fundus The superior portion of the body of the stomach above the level of the cardiac notch. Stomach: Anatomy is typically roomier, so babies tend to orient themselves head down so that their body and limbs occupy the larger portion of the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy .

Clinical relevance

The maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy has a diameter of about 10 cm, through which the fetus must pass.
The presentation and position of the fetus will determine how wide the fetus is (known as the “presenting fetal diameter”) as it attempts to pass through the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy .
Certain presentation/positions are more difficult (or even impossible) to pass through the pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy because of their large presenting diameter.
Knowledge of the presentation and position are required to safely manage labor and delivery.

Risk factors for fetal malpresentation

Multiparity (which can result in lax abdominal walls)
Multiple gestations (e.g., twins)
Prematurity Prematurity Neonatal Respiratory Distress Syndrome
Uterine abnormalities (e.g., leiomyomas, uterine septa)
Narrow pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy shapes
Fetal anomalies (e.g., hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage )
Placental anomalies (e.g., placenta previa Placenta Previa Abnormal placentation in which the placenta implants in the lower segment of the uterus (the zone of dilation) and may cover part or all of the opening of the cervix. It is often associated with serious antepartum bleeding and premature labor. Placental Abnormalities , in which the placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity covers the internal cervical os)
Polyhydramnios Polyhydramnios Polyhydramnios is a pathological excess of amniotic fluid. Common causes of polyhydramnios include fetal anomalies, gestational diabetes, multiple gestations, and congenital infections. Patients are often asymptomatic but may present with dyspnea, extremity swelling, or abdominal distention. Polyhydramnios (too much fluid)
Oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of Oligohydramnios (not enough fluid)
Malpresentation in a previous pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care

Epidemiology

Prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency rates for different malpresentations at term:

Vertex presentation, occiput posterior position: 1 in 19 deliveries
Breech presentation: 1 in 33 deliveries
Face presentation: 1 in 600–800 deliveries
Transverse lie: 1 in 833 deliveries
Compound presentation: 1 in 1500 deliveries

Presentation

Presentation describes which body part of the fetus will pass through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy first. Presentations include:

Cephalic: head down
Breech: bottom/feet down
Transverse presentation: shoulder
Compound presentation: an extremity presents alongside the primary presenting part

Cephalic presentations

Cephalic presentations can be categorized as:

Vertex presentation: chin Chin The anatomical frontal portion of the mandible, also known as the mentum, that contains the line of fusion of the two separate halves of the mandible (symphysis menti). This line of fusion divides inferiorly to enclose a triangular area called the mental protuberance. On each side, inferior to the second premolar tooth, is the mental foramen for the passage of blood vessels and a nerve. Melasma flexed, with the occipital Occipital Part of the back and base of the cranium that encloses the foramen magnum. Skull: Anatomy fontanel as the presenting part
Face presentation
Brow presentation: forehead Forehead The part of the face above the eyes. Melasma is the presenting part

Vertex presentation

Face presentation (mentum anterior position)

Brow presentation (mentum posterior position)

Breech presentations

Breech presentations can be categorized as:

Frank breech: bottom down, legs extended (50%–70%)
Complete breech: bottom down, hips and knees both flexed
Incomplete breech: 1 or both hips not completely flexed
Footling breech: feet down

Breech presentations: Frank (bottom down, legs extended), complete (bottom down, hips and knees both flexed), and footling (feet down) breech presentations

Transverse and compound presentations

Uncommon, but when they occur, the presenting fetal part is the shoulder.
If the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy begins dilating, the arm Arm The arm, or “upper arm” in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm: Anatomy may prolapse through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy .
In compound presentations, the most common situation is a hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand: Anatomy or arm Arm The arm, or “upper arm” in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm: Anatomy presenting with the head.

Shoulder presentation (transverse lie)

Neglected shoulder presentation resulting in arm prolapse during labor

Vertex presentation with a compound hand

Fetal malpresentation

Any presentation other than vertex
Clinically, this means breech, face, brow, and shoulder presentations.

Position describes the relation of the fetal presenting part to the maternal bony pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy .

Vertex positions

Positions for vertex presentations describe the position of the fetal occiput .

Identified on cervical exam as the area in the midline between the anterior and posterior fontanelles Fontanelles Physical Examination of the Newborn
Anterior, posterior, or transverse in relation to the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy
Being on the maternal right or left
Right or left occiput anterior
Right or left occiput posterior
Right or left occiput transverse
Direct occiput anterior or posterior
The most common positions (and easiest for vaginal delivery) are occiput anterior.

Overview of different vertex positions LOA: left occiput anterior LOP: left occiput posterior LOT: left occiput transverse OA occiput anterior OP: occiput posterior ROA: right occiput anterior ROP: right occiput posterior ROT: right occiput transverse

Face and brow positions

Positions for face and brow presentations describe the position of the chin Chin The anatomical frontal portion of the mandible, also known as the mentum, that contains the line of fusion of the two separate halves of the mandible (symphysis menti). This line of fusion divides inferiorly to enclose a triangular area called the mental protuberance. On each side, inferior to the second premolar tooth, is the mental foramen for the passage of blood vessels and a nerve. Melasma .

The chin Chin The anatomical frontal portion of the mandible, also known as the mentum, that contains the line of fusion of the two separate halves of the mandible (symphysis menti). This line of fusion divides inferiorly to enclose a triangular area called the mental protuberance. On each side, inferior to the second premolar tooth, is the mental foramen for the passage of blood vessels and a nerve. Melasma is referred to as the mentum.
Right or left mentum anterior
Right or left mentum posterior
Right or left mentum transverse
Direct mentum anterior or posterior

Face presentation (mentum posterior position)

Breech and shoulder positions

Positions for breech presentations describe the position of the sacrum Sacrum Five fused vertebrae forming a triangle-shaped structure at the back of the pelvis. It articulates superiorly with the lumbar vertebrae, inferiorly with the coccyx, and anteriorly with the ilium of the pelvis. The sacrum strengthens and stabilizes the pelvis. Vertebral Column: Anatomy . Similar to other presentations, they include anterior, posterior, and transverse and right, left, and direct.
Dorso-superior (back up)
Dorso-inferior (back down)

Dorso-inferior shoulder presentation

Dorso-superior shoulder presentation

Attitude and asynclitism

Attitude: amount of flexion Flexion Examination of the Upper Limbs or extension Extension Examination of the Upper Limbs of the fetal head
Lateral deflection of the sagittal Sagittal Computed Tomography (CT) suture to 1 side or the other
Mild degrees of asynclitism are normal.
More severe asynclitism increases the presenting fetal diameter and makes it more difficult for the fetal head to pass through the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy .

Fetal malposition

Commonly refers to any position other than right occiput anterior, left occiput anterior, or direct occiput anterior
All nonvertex presentations are also malpositioned.
The terms fetal malpresentation and fetal malposition are often used interchangeably.
The presenting diameter refers to the width of the presenting part.
The maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy is about 10 cm at its narrowest point; the infant must orient itself so that it can fit through.
Most commonly, the infant will move into a cephalic, vertex presentation, in 1 of the occiput anterior positions → presents the narrowest diameter
Vertex presentation: suboccipitobregmatic diameter, approximately 9.5 cm
Vertex presentation with deflexed head: occipitofrontal diameter, approximately 11.5 cm
Brow presentation: occipitomental diameter, approximately 13 cm
Face presentation: submentobregmatic diameter, approximately 9.5 cm

Diameters of the fetal head

Comparison of presentation, attitude, and presenting diameter

How to establish lie, presentation, and position

Delivery is managed differently depending on the presentation and position of the infant. This information can be established in several different ways:

Leopold’s maneuvers

Ultrasonography.

Cervical examination
Techniques using abdominal palpation Abdominal Palpation Abdominal Examination to determine the presentation of the fetus
The fetal head will be hard and round.
The lower body will be bulkier, nodular, and mobile.
The back will be hard and smooth.
The other side (anterior surface of the fetus) will be filled with irregular, mobile fetal parts.
Experienced providers can also estimate the fetal weight using these maneuvers.
Bedside abdominal ultrasonography can easily identify the fetal head and its orientation Orientation Awareness of oneself in relation to time, place and person. Psychiatric Assessment .
Quick bedside ultrasonography Bedside Ultrasonography ACES and RUSH: Resuscitation Ultrasound Protocols on admission to labor and delivery to assess fetal presentation is considered standard of care Standard of care The minimum acceptable patient care, based on statutes, court decisions, policies, or professional guidelines. Malpractice .
The fetal head will typically encompass the entire window and appear like a large white circle (the fetal skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy ).
Identification Identification Defense Mechanisms of the eyes can help determine position.
It is quick and easy to perform and presents minimal risk to mother and infant.
Allowing mothers to labor with infants in a noncephalic presentation significantly increases the risks to both of them.

Suprapubic bedside ultrasound confirming a cephalic presentation

Suprapubic bedside ultrasound showing the large white circle of the fetal skull, confirming a cephalic presentation F: fetal falx

Vaginal and cervical examination

As the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy dilates, the fetal fontanelles Fontanelles Physical Examination of the Newborn can be directly palpated.
Identifying the location of the fetal fontanelles Fontanelles Physical Examination of the Newborn allows the practitioner to establish the position.
Insert 1–2 fingers through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy posteriorly.
Sweep fingers along the fetal head moving anteriorly.
This maneuver allows for identification Identification Defense Mechanisms of the sagittal Sagittal Computed Tomography (CT) suture.
The fontanelles Fontanelles Physical Examination of the Newborn are then identified by moving along the sagittal Sagittal Computed Tomography (CT) suture.

Vertex presentations

Expectant management
All have high chances of successful vaginal delivery.

Compound presentations

Observation when labor is progressing normally (many compound presentations will resolve spontaneously intrapartum).
Can attempt to gently pinch the compound extremity trying to provoke the fetus into withdrawing the part (no good quality Quality Activities and programs intended to assure or improve the quality of care in either a defined medical setting or a program. The concept includes the assessment or evaluation of the quality of care; identification of problems or shortcomings in the delivery of care; designing activities to overcome these deficiencies; and follow-up monitoring to ensure effectiveness of corrective steps. Quality Measurement and Improvement evidence, but unlikely to be harmful)
Can attempt to manually replace the compound extremity
If labor is prolonged and the compound part remains, cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery (CD) should be performed.
Prolonged labor
Umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity prolapse
Increased maternal morbidity Morbidity The proportion of patients with a particular disease during a given year per given unit of population. Measures of Health Status from lacerations
Ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage of the compound part

Brow presentations

The majority spontaneously convert to a vertex presentation.
Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery may be required if labor is prolonged.

Face presentations

Management depends on the position.
Can be delivered vaginally by an experienced provider
Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery may be required.
Head is fully extended and unable to pass through the birth canal Birth canal Pelvis: Anatomy .
Normally, the fetal head flexes as it passes under the pubic bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types ; however, this is impossible in an MP position.
Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery is always required (unless the infant spontaneously rotates to a mentum anterior (MA) position).

There are 3 primary options for managing breech presentations: performing CD, attempting an external cephalic version to manually rotate the baby into a vertex presentation for attempted vaginal delivery, or a planned vaginal breech delivery (which is generally not done in the United States).

Natural history of breech presentations

Most infants will spontaneously rotate to a vertex presentation as the pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care progresses. At different gestational ages, the prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency of breech presentations is:

< 28 weeks: 20%–25%
32 weeks: 10%–15%
Term (> 37 weeks): 3%
Spontaneous version is possible even at > 40 weeks.
Flexed fetal legs
Polyhydramnios Polyhydramnios Polyhydramnios is a pathological excess of amniotic fluid. Common causes of polyhydramnios include fetal anomalies, gestational diabetes, multiple gestations, and congenital infections. Patients are often asymptomatic but may present with dyspnea, extremity swelling, or abdominal distention. Polyhydramnios
Longer umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity
Lack of fetal/uterine anomalies
Multiparity

Fetal risks associated with breech presentations

The following risks are associated with breech presentations in utero, regardless of mode of delivery:

↑ Association with congenital Congenital Chorioretinitis malformations
Torticollis Torticollis A symptom, not a disease, of a twisted neck. In most instances, the head is tipped toward one side and the chin rotated toward the other. The involuntary muscle contractions in the neck region of patients with torticollis can be due to congenital defects, trauma, inflammation, tumors, and neurological or other factors. Cranial Nerve Palsies
Developmental hip dysplasia

Fetal risks associated with vaginal breech delivery

The primary risk of a vaginal breech delivery is fetal head entrapment:

The fetal body delivers, but the head remains trapped in the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy .
Causes compression Compression Blunt Chest Trauma of the umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity running past the head (between the delivered umbilicus and the undelivered placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity )
Leads to hypoxia Hypoxia Sub-optimal oxygen levels in the ambient air of living organisms. Ischemic Cell Damage until head is delivered → ↑ risk of fetal death
The cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy may not be fully dilated enough to accommodate the head.
The fetal head may not fit through the bony pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy .
The mother’s expulsive efforts are unable to quickly deliver the head.
Umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity prolapse during labor → requires emergent CD
Birth injuries to the fetus (e.g., brachial plexus Brachial Plexus The large network of nerve fibers which distributes the innervation of the upper extremity. The brachial plexus extends from the neck into the axilla. In humans, the nerves of the plexus usually originate from the lower cervical and the first thoracic spinal cord segments (c5-c8 and T1), but variations are not uncommon. Peripheral Nerve Injuries in the Cervicothoracic Region injury)

Vaginal breech delivery

Vaginal breech deliveries for singleton gestations may be considered for certain low-risk women if vaginal delivery is strongly desired by the mother. In contrast, vaginal breech deliveries are done frequently for breech 2nd twins; the procedure is known as a breech extraction.

Mothers must be fully counseled on risks.
Mothers and infants should be monitored throughout labor with continuous electronic fetal heart rate Heart rate The number of times the heart ventricles contract per unit of time, usually per minute. Cardiac Physiology (FHR) and tocometry monitors.
Mothers should understand that a CD will be recommended if there are signs of fetal distress or prolonged labor.
Avoid artificial rupture of membranes to ↓ risk of cord prolapse.
Frank or complete breech presentation with no hyperextension of the fetal head on ultrasonography
No contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation to a vaginal birth
No prior CDs
Prior successful vaginal deliveries (i.e., multiparity)
Gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care ≥ 36 weeks
Spontaneous labor
Normal bony pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy shown on X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests
Estimated fetal weight Estimated Fetal Weight Obstetric Imaging between approximately 2500 and 3500 grams (exact range varies based on clinician Clinician A physician, nurse practitioner, physician assistant, or another health professional who is directly involved in patient care and has a professional relationship with patients. Clinician–Patient Relationship )
Immediately after delivery of the 1st twin in the cephalic presentation, the physician reaches up into the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy , manually grabs the infant’s legs, and gently guides them down through the birth canal Birth canal Pelvis: Anatomy while the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy is still fully dilated.
↓ Risk of head entrapment compared to singleton vaginal breech deliveries

External cephalic version

An external cephalic version (ECV) is a procedure in which the physician attempts to manually rotate the fetus from a breech to a cephalic presentation by pushing on the maternal abdomen.

Approximately 50%–60% (higher in multiparous Multiparous A woman with prior deliveries Normal and Abnormal Labor than in nulliparous women)
97% of infants remained cephalic at birth.
86% delivered vaginally.
Women who are candidates for ECV should be counseled on their options to attempt an ECV, or they may simply elect to schedule a CD.
Infant is full term in case emergent CD is required because of complications from the procedure (e.g., placental abruption Placental Abruption Premature separation of the normally implanted placenta from the uterus. Signs of varying degree of severity include uterine bleeding, uterine muscle hypertonia, and fetal distress or fetal death. Antepartum Hemorrhage ).
Better ratio of infant size to fluid level than later in pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care
Allows infant more time for spontaneous version than if the procedure was done earlier
After a successful version, the mother can await spontaneous labor or be induced immediately, depending on the situation.
There is still a chance that the infant may spontaneously rotate between the failed ECV and the planned CD date; therefore, presentation should always be checked immediately prior to CD.
Another contraindication for a vaginal delivery (e.g., placenta previa Placenta Previa Abnormal placentation in which the placenta implants in the lower segment of the uterus (the zone of dilation) and may cover part or all of the opening of the cervix. It is often associated with serious antepartum bleeding and premature labor. Placental Abnormalities )
Severe oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of Oligohydramnios
Nonreassuring fetal monitoring Fetal monitoring The primary goals of antepartum testing and monitoring are to assess fetal well-being, identify treatable situations that may cause complications, and evaluate for chromosomal abnormalities. These tests are divided into screening tests (which include cell-free DNA testing, serum analyte testing, and nuchal translucency measurements), and diagnostic tests, which provide a definitive diagnosis of aneuploidy and include chorionic villus sampling (CVS) and amniocentesis. Antepartum Testing and Monitoring prior to the procedure
A hyperextended fetal head
Significant fetal or uterine anomalies
Leads to fetal and maternal hemorrhage
An immediate CD is required.
If the version was successful, labor should be induced immediately.
If the version was unsuccessful, the mother should undergo immediate CD.
Cord prolapse: can occur with PROM PROM Prelabor rupture of membranes (PROM), previously known as premature rupture of membranes, refers to the rupture of the amniotic sac before the onset of labor. Prelabor rupture of membranes may occur in term or preterm pregnancies. Prelabor Rupture of Membranes and requires immediate/emergent CD.
Common during the procedure, but typically resolves shortly after pressure on the abdomen is released.
If distress persists, the mother should undergo an immediate CD.

Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery

Scheduled at 39 weeks’ gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care (WGA) if the infant is known to be in the breech presentation.
Alternative option to attempting ECV
Postpartum hemorrhage Postpartum hemorrhage Postpartum hemorrhage is one of the most common and deadly obstetric complications. Since 2017, postpartum hemorrhage has been defined as blood loss greater than 1,000 mL for both cesarean and vaginal deliveries, or excessive blood loss with signs of hemodynamic instability. Postpartum Hemorrhage
Postpartum endomyometritis
Maternal injury
Longer recovery time postpartum
Complications in future pregnancies (e.g., placenta previa Placenta Previa Abnormal placentation in which the placenta implants in the lower segment of the uterus (the zone of dilation) and may cover part or all of the opening of the cervix. It is often associated with serious antepartum bleeding and premature labor. Placental Abnormalities , placenta accreta Placenta Accreta Abnormal placentation in which all or parts of the placenta are attached directly to the myometrium due to a complete or partial absence of decidua. It is associated with postpartum hemorrhage because of the failure of placental separation. Placental Abnormalities , uterine rupture Uterine Rupture A complete separation or tear in the wall of the uterus with or without expulsion of the fetus. It may be due to injuries, multiple pregnancies, large fetus, previous scarring, or obstruction. Antepartum Hemorrhage )
Maternal request (mother declines ECV attempt)
ECV contraindicated
ECV unsuccessful
Fetal distress during labor

Management of transverse presentations

As with breech presentations, mothers may be offered an attempt at ECV or a CD.
Unlike breech presentations, vaginal transverse delivery is always contraindicated.
Hofmeyr, G.J. (2021). Overview of breech presentation. In Barss, V.A. (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/overview-of-breech-presentation
Hofmeyr, G.J. (2021). Delivery of the singleton fetus in breech presentation. In Barss, V.A. (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/delivery-of-the-singleton-fetus-in-breech-presentation
Hofmeyr, G.J. (2021). External cephalic version. In Barss, V.A. (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/external-cephalic-version
Julien, S., and Galerneau, F. (2021). Face and brow presentations in labor. In Barss, V.A., (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/face-and-brow-presentations-in-labor
Strauss, R.A., Herrera, C.A. (2021). Transverse fetal lie. In Barss, V.A., (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/transverse-fetal-lie
Barth, W.H. (2021). Compound fetal presentation. In Barss, V.A., (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/compound-fetal-presentation
Cunningham, F. G., Leveno, K. J., et al. (2010). Williams Obstetrics, 23rd ed., pp. 374‒382.

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Sonographic evaluation of the fetal head position and attitude during labor

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Add to Mendeley
arrest of descent
asynclitism
brow presentation
cephalopelvic disproportion
face presentation
fetal attitude
head deflexion
intrapartum sonography
labor dystocia
occiput position
protracted active phase of labor
sinciput presentation

Introduction

Intrapartum assessment of malposition, intrapartum assessment of malpresentation and asynclitism.

Malposition, malpresentation, and asynclitism: toward a sonographic classification of labor dystocia?

Conclusions

Acknowledgments, supplementary data (1), article metrics, related articles.

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Labour and Delivery Care Module: 8. Abnormal Presentations and Multiple Pregnancies

Study session 8 abnormal presentations and multiple pregnancies, introduction.

In previous study sessions of this module, you have been introduced to the definitions, signs, symptoms and stages of normal labour, and about the ‘normal’ vertex presentation of the fetus during delivery. In this study session, you will learn about the most common abnormal presentations (breech, shoulder, face or brow), their diagnostic criteria and the required actions you need to take to prevent complications developing during labour. Taking prompt action may save the life of the mother and her baby if the delivery becomes obstructed because the baby is in an abnormal presentation. We will also tell you about twin births and the complications that may result if the two babies become ‘locked’ together, preventing either of them from being born.

Learning Outcomes for Study Session 8

After studying this session, you should be able to:

8.1 Define and use correctly all of the key words printed in bold . (SAQs 8.1 and 8.2)

8.2 Describe how you would identify a fetus in the vertex presentation and distinguish this from common malpresentations and malpositions. (SAQs 8.1 and 8.2)

8.3 Describe the causes and complications for the fetus and the mother of fetal malpresentation during full term labour. (SAQ 8.3)

8.4 Describe how you would identify a multiple pregnancy and the complications that may arise. (SAQ 8.4)

8.5 Explain when and how you would refer a woman in labour due to abnormal fetal presentation or multiple pregnancy. (SAQ 8.4)

8.1 Normal and abnormal presentations

8.1.1 vertex presentation.

In about 95% of deliveries, the part of the fetus which arrives first at the mother’s pelvic brim is the highest part of the fetal head, which is called the vertex (Figure 8.1). This presentation is called the vertex presentation . Notice that the baby’s chin is tucked down towards its chest, so that the vertex is the leading part entering the mother’s pelvis. The baby’s head is said to be ‘well-flexed’ in this position.

A baby in the well-flexed vertex presentation before birth, relative to the mother’s pelvis

During early pregnancy, the baby is the other way up — with its bottom pointing down towards the mother’s cervix — which is called the breech presentation . This is because during its early development, the head of the fetus is bigger than its buttocks; so in the majority of cases, the head occupies the widest cavity, i.e. the fundus (rounded top) of the uterus. As the fetus grows larger, the buttocks become bigger than the head and the baby spontaneously reverses its position, so its buttocks occupy the fundus. In short, in early pregnancy, the majority of fetuses are in the breech presentation and later in pregnancy most of them make a spontaneous transition to the vertex presentation.

8.1.2 Malpresentations

You will learn about obstructed labour in Study Session 9.

When the baby presents itself in the mother’s pelvis in any position other than the vertex presentation, this is termed an abnormal presentation, or m alpresentation . The reason for referring to this as ‘abnormal’ is because it is associated with a much higher risk of obstruction and other birth complications than the vertex presentation. The most common types of malpresentation are termed breech, shoulder, face or brow. We will discuss each of these in turn later. Notice that the baby can be ‘head-down’ but in an abnormal presentation, as in face or brow presentations, when the baby’s face or forehead (brow) is the presenting part.

8.1.3 Malposition

Although it may not be so easy for you to identify this, the baby can also be in an abnormal position even when it is in the vertex presentation. In a normal delivery, when the baby’s head has engaged in the mother’s pelvis, the back of the baby’s skull (the occiput ) points towards the front of the mother’s pelvis (the pubic symphysis ), where the two pubic bones are fused together. This orientation of the fetal skull is called the occipito-anterior position (Figure 8.2a). If the occiput (back) of the fetal skull is towards the mother’s back, this occipito-posterior position (Figure 8.2b) is a vertex malposition , because it is more difficult for the baby to be born in this orientation. The good thing is that more than 90% of babies in vertex malpositions undergo rotation to the occipito-anterior position and are delivered normally.

You learned the directional positions: anterior/in front of and posterior/behind or in the back of, in the Antenatal Care Module, Part 1, Study Session 3.

Note that the fetal skull can also be tilted to the left or to the right in either the occipito-anterior or occipito-posterior positions.

Possible positions of the fetal skull when the baby is in the vertex presentation and the mother is lying on her back:

8.2 Causes and consequences of malpresentations and malpositions

In the majority of individual cases it may not be possible to identify what caused the baby to be in an abnormal presentation or position during delivery. However, the general conditions that are thought to increase the risk of malpresentation or malposition are listed below:

Multiple pregnancy is the subject of Section 8.7 of this study session. You learned about placenta previa in the Antenatal Care Module, Study Session 21.

Abnormally increased or decreased amount of amniotic fluid
A tumour (abnormal tissue growth) in the uterus preventing the spontaneous inversion of the fetus from breech to vertex presentation during late pregnancy
Abnormal shape of the pelvis
Laxity (slackness) of muscular layer in the walls of the uterus
Multiple pregnancy (more than one baby in the uterus)
Placenta previa (placenta partly or completely covering the cervical opening).

If the baby presents at the dilating cervix in an abnormal presentation or malposition, it will more difficult (and may be impossible) for it to complete the seven cardinal movements that you learned about in Study Sessions 3 and 5. As a result, birth is more difficult and there is an increased risk of complications, including:

You learned about PROM in Study Session 17 of the Antenatal Care Module, Part 2.

Premature rupture of the fetal membranes (PROM)
Premature labour
Slow, erratic, short-lived contractions
Uncoordinated and extremely painful contractions, with slow or no progress of labour
Prolonged and obstructed labour, leading to a ruptured uterus (see Study Sessions 9 and 10 of this Module)
Postpartum haemorrhage (see Study Session 11)
Fetal and maternal distress, which may lead to the death of the baby and/or the mother.

With these complications in mind, we now turn your attention to the commonest types of malpresentation and how to recognise them.

8.3 Breech presentation

In a b reech presentation , the fetus lies with its buttocks in the lower part of the uterus, and its buttocks and/or the feet are the presenting parts during delivery. Breech presentation occurs on average in 3–4% of deliveries after 34 weeks of pregnancy.

When is the breech position the normal position for the fetus?

During early pregnancy the baby’s bottom points down towards the mother’s cervix, and its head (the largest part of the fetus at this stage of development) occupies the fundus (rounded top) of the uterus, which is the widest part of the uterine cavity.

8.3.1 Causes of breech presentation

You can see a transverse lie in Figure 8.7 later in this study session.

In the majority of cases there is no obvious reason why the fetus should present by the breech at full term. In practice, what is commonly observed is the association of breech presentation at delivery with a transverse lie earlier in the pregnancy, i.e. the fetus lies sideways across the mother’s abdomen, facing a sideways implanted placenta. It is thought that when the placenta is in front of the baby’s face, it may obstruct the normal process of inversion, when the baby turns head-down as it gets bigger during the pregnancy. As a result, the fetus turns in the other direction and ends in the breech presentation. Some other circumstances that are thought to favour a breech presentation during labour include:

Premature labour, beginning before the baby undergoes spontanous inversion from breech to vertex presentation
Multiple pregnancy, preventing the normal inversion of one or both babies
Polyhydramnios: excessive amount of amniotic fluid, which makes it more difficult for the fetal head to ‘engage’ with the mother’s cervix (polyhydramnios is pronounced ‘poll-ee-hy-dram-nee-oss’. Hydrocephaly is pronounced ‘hy-droh-keff-all-ee’)
Hydrocephaly (‘water on the brain’) i.e. an abnormally large fetal head due to excessive accumulation of fluid around the brain
Placenta praevia
Breech delivery in the previous pregnancy
Abnormal formation of the uterus.

8.3.2 Diagnosis of breech presentation

On abdominal palpation the fetal head is found above the mother’s umbilicus as a hard, smooth, rounded mass, which gently ‘ballots’ (can be rocked) between your hands.

Why do you think a mass that ‘ballots’ high up in the abdomen is a sign of breech presentation? (You learned about this in Study Session 11 of the Antenatal Care Module.)

The baby’s head can ‘rock’ a little bit because of the flexibility of the baby’s neck, so if there is a rounded, ballotable mass above the mother’s umbilicus it is very likely to be the baby’s head. If the baby was ‘bottom-up’ (vertex presentation) the whole of its back will move of you try to rock the fetal parts at the fundus (Figure 8.3).

(a) The whole back of a baby in the vertex position will move if you rock it at the fundus; (b) The head can be ‘rocked’ and the back stays still in a breech presentation.

Once the fetus has engaged and labour has begun, the breech baby’s buttocks can be felt as soft and irregular on vaginal examination. They feel very different to the relatively hard rounded mass of the fetal skull in a vertex presentation. When the fetal membranes rupture, the buttocks and/or feet can be felt more clearly. The baby’s anus may be felt and fresh thick, dark meconium may be seen on your examining finger. If the baby’s legs are extended, you may be able to feel the external genitalia and even tell the sex of the baby before it is born.

8.3.3 Types of breech presentation

There are three types of breech presentation, as illustrated in Figure 8.4. They are:

Complete breech is characterised by flexion of the legs at both hips and knee joints, so the legs are bent underneath the baby.
Frank breech is the commonest type of breech presentation, and is characterised by flexion at the hip joints and extension at the knee joints, so both the baby’s legs point straight upwards.
Footling breech is when one or both legs are extended at the hip and knee joint and the baby presents ‘foot first’.

Figure 8.4 Different types of breech presentation.

8.3.4 Risks of breech presentation

Regardless of the type of breech presentation, there are significant associated risks to the baby. They include:

The fetal head gets stuck (arrested) before delivery
Labour becomes obstructed when the fetus is disproportionately large for the size of the maternal pelvis
Cord prolapse may occur, i.e. the umbilical cord is pushed out ahead of the baby and may get compressed against the wall of the cervix or vagina
Premature separation of the placenta (placental abruption)
Birth injury to the baby, e.g. fracture of the arms or legs, nerve damage, trauma to the internal organs, spinal cord damage, etc.

A breech birth may also result in trauma to the mother’s birth canal or external genitalia through being overstretched by the poorly fitting fetal parts.

Cord prolapse in a normal (vertex) presentation was illustrated in Study Session 17 of the Antenatal Care Module, and placental abruption was covered in Study Session 21.

What will be the effect on the baby if it gets stuck, the labour is obstructed, the cord prolapses, or placental abruption occurs?

The result will be hypoxia , i.e. it will be deprived of oxygen, and may suffer permanent brain damage or die.

You learned about the causes and consequences of hypoxia in the Antenatal Care Module.

8.4 Face presentation

Face presentation occurs when the baby’s neck is so completely extended (bent backwards) that the occiput at the back of the fetal skull touches the baby’s own spine (see Figure 8.5). In this position, the baby’s face will present to you during delivery.

5 Face presentation. (a) The baby’s chin is facing towards the front of the mother’s pelvis; (b) the chin is facing towards the mother’s backbone.

Refer the mother if a baby in the chin posterior face presentation does not rotate and the labour is prolonged.

The incidence of face presentation is about 1 in 500 pregnancies in full term labours. In Figure 8.5, you can see how flexed the head is at the neck. Babies who present in the ‘chin posterior’ position (on the right in Figure 8.5) usually rotate spontaneously during labour, and assume the ‘chin anterior’ position, which makes it easier for them to be born. However, they are unlikely to be delivered vaginally if they fail to undergo spontaneous rotation to the chin anterior position, because the baby’s chin usually gets stuck against the mother’s sacrum (the bony prominence at the back of her pelvis). A baby in this position will have to be delivered by caesarean surgery.

8.4.1 Causes of face presentation

The causes of face presentation are similar to those already described for breech births:

Laxity (slackness) of the uterus after many previous full-term pregnancies
Multiple pregnancy
Polyhydramnios (excessive amniotic fluid)
Congenital abnormality of the fetus (e.g. anencephaly, which means no or incomplete skull bones)
Abnormal shape of the mother’s pelvis.

8.4.2 Diagnosis of face presentation

Face presentation may not be easily detected by abdominal palpation, especially if the chin is in the posterior position. On abdominal examination, you may feel irregular shapes, formed because the fetal spine is curved in an ‘S’ shape. However, on vaginal examination, you can detect face presentation because:

The presenting part will be high, soft and irregular.
When the cervix is sufficiently dilated, you may be able to feel parts of the face, such as the orbital ridges above the eyes, the nose or mouth, gums, or bony chin.
If the membranes are ruptured, the baby may suck your examining finger!

But as labour progresses, the baby’s face becomes o edematous (swollen with fluid), making it more difficult to distinguish from the soft shape you will feel in a breech presentation.

8.4.3 Complications of face presentation

Complications for the fetus include:

Obstructed labour and ruptured uterus
Cord prolapse
Facial bruising
Cerebral haemorrhage (bleeding inside the fetal skull).

8.5 Brow presentation

In brow presentation , the baby’s head is only partially extended at the neck (compare this with face presentation), so its brow (forehead) is the presenting part (Figure 8.6). This presentation is rare, with an incidence of 1 in 1000 deliveries at full term.

8.5.1 Possible causes of brow presentation

You have seen all of these factors before, as causes of other malpresentations:

Lax uterus due to repeated full term pregnancy
Polyhydramnios

8.5.2 Diagnosis of brow presentation

Brow presentation is not usually detected before the onset of labour, except by very experienced birth attendants. On abdominal examination, the head is high in the mother’s abdomen, appears unduly large and does not descend into the pelvis, despite good uterine contractions. On vaginal examination, the presenting part is high and may be difficult to reach. You may be able to feel the root of the nose, eyes, but not the mouth, tip of the nose or chin. You may also feel the anterior fontanel, but a large caput (swelling) towards the front of the fetal skull may mask this landmark if the woman has been in labour for some hours.

Recall the appearance of a normal caput over the posterior fontanel shown in Figure 4.4 earlier in this Module.

8.5.3 Complications of brow presentation

The complications of brow presentation are much the same as for other malpresentations:

Cerebral haemorrhage.

Which are you more likely to encounter — face or brow presentations?

Face presentation, which occurs in 1 in 500 full term labours. Brow presentation is more rare, at 1 in 1,000 full term labours.

8.6 Shoulder presentation

Shoulder presentation is rare at full term, but may occur when the fetus lies transversely across the uterus (Figure 8.7), if it stopped part-way through spontaneous inversion from breech to vertex, or it may lie transversely from early pregnancy. If the baby lies facing upwards, its back may be the presenting part; if facing downwards its hand may emerge through the cervix. A baby in the transverse position cannot be born through the vagina and the labour will be obstructed. Refer babies in shoulder presentation urgently.

8.6.1 Causes of shoulder presentation

Causes of shoulder presentation could be maternal or fetal factors.

Maternal factors include:

Lax abdominal and uterine muscles: most often after several previous pregnancies
Uterine abnormality
Contracted (abnormally narrow) pelvis.

Fetal factors include:

Preterm labour
Placenta previa.

What do ‘placenta previa’ and ‘polyhydramnios’ indicate?

Placenta previa is when the placenta is partly or completely covering the cervical opening. Polyhydramnios is an excess of amniotic fluid. They are both potential causes of malpresentation.

8.6.2 Diagnosis of shoulder presentation

On abdominal palpation, the uterus appears broader and the height of the fundus is less than expected for the period of gestation, because the fundus is not occupied by either the baby’s head or buttocks. You can usually feel the head on one side of the mother’s abdomen. On vaginal examination, in early labour, the presenting part may not be felt, but when the labour is well progressed, you may feel the baby’s ribs. When the shoulder enters the pelvic brim, the baby’s arm may prolapse and become visible outside the vagina.

8.6.3 Complications of shoulder presentation

Complications include:

Trauma to a prolapsed arm
Fetal hypoxia and death.

Remember that a shoulder presentation means the baby cannot be born through the vagina; if you detect it in a woman who is already in labour, refer her urgently to a higher health facility.

8.7 Multiple pregnancy

In this section, we turn to the subject of multiple pregnancy , when there is more than one fetus in the uterus. More than 95% of multiple pregnancies are twins (two fetuses), but there can also be triplets (three fetuses), quadruplets (four fetuses), quintuplets (five fetuses), and other higher order multiples with a declining chance of occurrence. The spontaneous occurrence of twins varies by country : it is lowest in East Asia n countries like Japan and China (1 out of 1000 pregnancies are fraternal or non-identical twins), and highest in black Africans , particularly in Nigeria , where 1 in 20 pr egnancies are fraternal twins. In general, compared to single babies, multiple pregnancies are highly associated with early pregnancy loss and high perinatal mortality, mainly due to prematurity.

8.7.1 Types of twin pregnancy

Twins may be identical (monozygotic) or non-identical and fraternal (dizigotic). Monozygotic twins develop from a single fertilised ovum (the zygote), so they are always the same sex and they share the same placenta . By contrast, dizygotic twins develop from two different zygotes, so they can have the same or different sex, and they have separate placenta s . Figure 8.8 shows the types of twin pregnancy and the processes by which they are formed.

Types of twin pregnancy: (a) Fraternal or non-identical twins usually each have a placenta of their own, although they can fuse if the two placentas lie very close together. (b) Identical twins always share the same placenta, but usually they have their own fetal membranes.

8.7.2 Diagnosis of twin pregnancy

On abdominal examination you may notice that:

The size of the uterus is larger than the expected for the period for gestation.
The uterus looks round and broad, and fetal movement may be seen over a large area. (The shape of the uterus at term in a singleton pregnancy in the vertex presentation appears heart-shaped rounder at the top and narrower at the bottom.)
Two heads can be felt.
Two fetal heart beats may be heard if two people listen at the same time, and they can detect at least 10 beats different (Figure 8.6).
Ultrasound examination can make an absolute diagnosis of twin pregnancy.

Two people listen either side of the pregnant woman. Each taps in rhythm with the heartbeat they can hear. The pregnant woman says that their tapping is different and maybe she is having twins.

8.7.3 Consequences of twin pregnancy

Women who are pregnant with twins are more prone to suffer with the minor disorders of pregnancy, like morning sickness, nausea and heartburn. Twin pregnancy is one cause of hyperemesis gravidarum (persistent, severe nausea and vomiting). Mothers of twins are also more at risk of developing iron and folate-deficiency anaemia during pregnancy.

Can you suggest why anaemia is a greater risk in multiple pregnancies?

The mother has to supply the nutrients to feed two (or more) babies; if she is not getting enough iron and folate in her diet, or through supplements, she will become anaemic.

Other complications include the following:

Pregnancy-related hypertensive disorders like pre-eclampsia and eclampsia are more common in twin pregnancies.
Pressure symptoms may occur in late pregnancy due to the increased weight and size of the uterus.
Labour often occurs spontaneously before term, with p remature delivery or premature rupture of membranes (PROM) .
Respiratory deficit ( shortness of breath, because of fast growing uterus) is another common problem.

Twin babies may be small in comparison to their gestational age and more prone to the complications associated with low birth weight (increased vulnerability to infection, losing heat, difficulty breastfeeding).

You will learn about low birth weight babies in detail in the Postnatal Care Module.

Malpresentation is more common in twin pregnancies, and they may also be ‘locked’ at the neck with one twin in the vertex presentation and the other in breech. The risks associated with malpresentations already described also apply: prolapsed cord, poor uterine contraction, prolonged or obstructed labour, postpartum haemorrhage, and fetal hypoxia and death.
Conjoined twins (fused twins, joined at the head, chest, or abdomen, or through the back) may also rarely occur.

8.8 Management of women with malpresentation or multiple pregnancy

As you have seen in this study session, any presentation other than vertex has its own dangers for the mother and baby. For this reason, all women who develop abnormal presentation or multiple pregnancy should ideally have skilled care by senior health professionals in a health facility where there is a comprehensive emergency obstetric service. Early detection and referral of a woman in any of these situations can save her life and that of her baby.

What can you do to reduce the risks arising from malpresentation or multiple pregnancy in women in your care?

During focused antenatal care of the pregnant women in your community, at every visit after 36 weeks of gestation you should check for the presence of abnormal fetal presentation. If you detect abnormal presentation or multiple pregnancy, you should refer the woman before the onset of labour.

Summary of Study Session 8

In Study Session 8, you learned that:

During early pregnancy, babies are naturally in the breech position, but in 95% of cases they spontaneously reverse into the vertex presentation before labour begins.
Malpresentation or malposition of the fetus at full term increases the risk of obstructed labour and other birth complications.
Common causes of malpresentations/malpositions include: excess amniotic fluid, abnormal shape and size of the pelvis; uterine tumour; placenta praevia; slackness of uterine muscles (after many previous pregnancies); or multiple pregnancy.
Common complications include: premature rupture of membranes, premature labour, prolonged/obstructed labour; ruptured uterus; postpartum haemorrhage; fetal and maternal distress which may lead to death.
Vertex malposition is when the fetal head is in the occipito-posterior position — i.e. the back of the fetal skull is towards the mother’s back instead of pointing towards the front of the mother’s pelvis. 90% of vertex malpositions rotate and deliver normally.
Breech presentation (complete, frank or footling) is when the baby’s buttocks present during labour. It occurs in 3–4% of labours after 34 weeks of pregnancy and may lead to obstructed labour, cord prolapse, hypoxia, premature separation of the placenta, birth injury to the baby or to the birth canal.
Face presentation is when the fetal head is bent so far backwards that the face presents during labour. It occurs in about 1 in 500 full term labours. ‘Chin posterior’ face presentations usually rotate spontaneously to the ‘chin anterior’ position and deliver normally. If rotation does not occur, a caesarean delivery is likely to be necessary.
Brow presentation is when the baby’s forehead is the presenting part. It occurs in about 1 in 1000 full term labours and is difficult to detect before the onset of labour. Caesarean delivery is likely to be necessary.
Shoulder presentation occurs when the fetal lie during labour is transverse. Once labour is well progressed, vaginal examination may feel the baby’s ribs, and an arm may sometimes prolapse. Caesarean delivery is always required unless a doctor or midwife can turn the baby head-down.
Multiple pregnancies are always at high risk of malpresentation. Mothers need greater antenatal care, and twins are more prone to complications associated with low birth weight and prematurity.
Any presentation other than vertex after 34 weeks of gestation is considered as high risk to the mother and to her baby. Do not attempt to turn a malpresenting or malpositioned baby! Refer the mother for emergency obstetric care.

Self-Assessment Questions (SAQs) for Study Session 8

Now that you have completed this study session, you can assess how well you have achieved its Learning Outcomes by answering the following questions. Write your answers in your Study Diary and discuss them with your Tutor at the next Study Support Meeting. You can check your answers with the Notes on the Self-Assessment Questions at the end of this Module.

SAQ 8.1 (tests Learning Outcomes 8.1, 8.2 and 8.4)

Which of the following definitions are true and which are false? Write down the correct definition for any which you think are false.

A Fundus — the ‘rounded top’ and widest cavity of the uterus.

B Complete breech — where the legs are bent at both hips and knee joints and are folded underneath the baby.

C Frank breech — where the breech is so difficult to treat that you have to be very frank and open with the mother about the difficulties she will face in the birth.

D Footling breech — when one or both legs are extended so that the baby presents ‘foot first’.

E Hypoxia — the baby gets too much oxygen.

F Multiple pregnancy — when a mother has had many babies previously.

G Monozygotic twins — develop from a single fertilised ovum (the zygote). They can be different sexes but they share the same placenta.

H Dizygotic twins — develop from two zygotes. They have separate placentas, and can be of the same sex or different sexes.

A is true. The fundus is the ‘rounded top’ and widest cavity of the uterus.

B is true. Complete breech is where the legs are bent at both hips and knee joints and are folded underneath the baby.

C is false . A frank breech is the most common type of breech presentation and is when the baby’s legs point straight upwards (see Figure 8.4).

D is true. A footling breech is when one or both legs are extended so that the baby presents ‘foot first’.

E is false . Hypoxia is when the baby is deprived of oxygen and risks permanent brain damage or death.

F is false. Multiple pregnancy is when there is more than one fetus in the uterus.

G is false. Monozygotic twins develop from a single fertilised ovum (the zygote), and they are always the same sex , as well as sharing the same placenta.

H is true. Dizygotic twins develop from two zygotes, have separate placentas, and can be of the same or different sexes.

SAQ 8.2 (tests Learning Outcomes 8.1 and 8.2)

What are the main differences between normal and abnormal fetal presentations? Use the correct medical terms in bold in your explanation.

In a normal presentation, the vertex (the highest part of the fetal head) arrives first at the mother’s pelvic brim, with the occiput (the back of the baby’s skull) pointing towards the front of the mother’s pelvis (the pubic symphysis ).

Abnormal presentations are when there is either a vertex malposition (the occiput of the fetal skull points towards the mother’s back instead towards of the pubic symphysis), or a malpresentation (when anything other than the vertex is presenting): e.g. breech presentation (buttocks first); face presentation (face first); brow presentation (forehead first); and shoulder presentation (transverse fetal).

SAQ 8.3 (tests Learning Outcomes 8.3 and 8.5)

a. List the common complications of malpresentations or malposition of the fetus at full term.
b. What action should you take if you identify that the fetus is presenting abnormally and labour has not yet begun?
c. What should you not attempt to do?
a. The common complications of malpresentation or malposition of the fetus at full term include: premature rupture of membranes, premature labour, prolonged/obstructed labour; ruptured uterus; postpartum haemorrhage; fetal and maternal distress which may lead to death.
b. You should refer the mother to a higher health facility – she may need emergency obstetric care.
c. You should not attempt to turn the baby by hand. This should only be attempted by a specially trained doctor or midwife and should only be done at a health facility.

SAQ 8.4 (tests Learning Outcomes 8.4 and 8.5)

A pregnant woman moves into your village who is already at 37 weeks gestation. You haven’t seen her before. She tells you that she gave birth to twins three years ago and wants to know if she is having twins again this time.

a. How would you check this?
b. If you diagnose twins, what would you do to reduce the risks during labour and delivery?
Is the uterus larger than expected for the period of gestation?
What is its shape – is it round (indicative of twins) or heart-shaped (as in a singleton pregnancy)?
Can you feel more than one head?
Can you hear two fetal heartbeats (two people listening at the same time) with at least 10 beats difference?
If there is access to a higher health facility, and you are still not sure, try and get the woman to it for an ultrasound scan.
Be extra careful to check that the mother is not anaemic.
Encourage her to rest and put her feet up to reduce the risk of increased blood pressure or swelling in her legs and feet.
Be alert to the increased risk of pre-eclampsia.
Expect her to go into labour before term, and be ready to get her to the health facility before she goes into labour, going with her if at all possible.
Get in early touch with that health facility to warn them to expect a referral from you.
Make sure that transport is ready to take her to a health facility when needed.

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Abnormal Fetal Position and Presentation

Under normal circumstances, a baby is in the vertex (cephalic) position before delivery. In the vertex position, the baby’s head is at the lower part of the abdomen, and the baby is born head-first. However, some babies present differently before delivery. Abnormal presentations may place the baby at risk of experiencing umbilical cord problems and/or a birth trauma .

What is the difference between fetal presentation and position?

In the womb, a fetus has both a presentation and a position .

Presentation refers to the part of the baby’s body that leads out of the birth canal. For example, if a baby’s rear is set to come out of the birth canal first, the baby is said to be in “breech presentation.”
Position refers to the direction the baby is facing in relation to the mother’s spine. A baby could be lying face-first against a mother’s spine or face up towards the mother’s belly.

What way should a baby come out during birth?

Vertex presentation is the ‘normal’ position for birth and the lowest-risk presentation for vaginal birth.

In vertex presentation, the baby is positioned head-first with back of the head entering the birth canal first. In this position, the baby’s chin is tucked into their chest and they are facing the mother’s back (occipito-anterior position).

Any position other than vertex position is abnormal and can make vaginal delivery much more difficult or sometimes impossible . If a baby’s chin isn’t tucked into their chest, they may come out face-first (face presentation), which can cause birth injury.

What happens if a baby isn’t in the standard vertex position during birth?

Before vaginal delivery, the baby must be in the standard vertex presentation and within the normal range for weight and size. This helps ensure the safety of both baby and mother during labor.

When the baby’s size or position is abnormal, physicians should usually intervene . This may mean simple manual procedures to help reposition the baby or, in many cases, a planned C-section delivery . Healthcare professionals must identify and quickly resolve issues related to fetal size, weight, and presentation. Failing to intervene is medical malpractice .

Numerous complications may result from abnormal weight, size, abnormal position, or abnormal presentation.

Should I contact a lawyer?

Abnormal presentation, if mishandled, can cause birth injuries. If you have any concerns about your baby’s labor and delivery, a consultation with an attorney is completely free. A birth injury lawyer can provide insight about potential medical malpractice.

Compound presentation

In a compound presentation , there are multiple presenting parts. Most commonly, the baby’s head and an arm come out at the same time. Sometimes compound presentation can occur with twins where the head of the first twin presents with the extremity of the second twin.

Risk factors for compound presentation include:

Prematurity
Intrauterine growth restriction (IUGR)
Multiple gestations ( twins , triplets, etc.)
Polyhydramnios (too much amniotic fluid)
A large pelvis
External cephalic version
Rupture of membranes at high station

Compound presentations can be detected via ultrasound before the mother’s water breaks. During labor, a cervical examination finds compound presentation.

If a mother has polyhydramnios, the risk of compound presentation is higher. The flow of amniotic fluid when the membranes rupture can sweep extremities into the birth canal or cause a cord prolapse , which is a medical emergency.

If compound presentation continues, it is likely to cause dystocia (the baby becoming stuck in the birth canal), which is also a medical emergency. Often, the safest way to deliver a baby with compound presentation is C-section.

Complications like dystocia and cord prolapse carry risks of severe adverse outcomes, including cerebral palsy , intellectual and developmental disabilities, and hypoxic-ischemic encephalopathy (HIE).

Limb presentation

Limb presentation during childbirth means that the part of the baby’s body that emerges first is a limb – an arm or a leg. Babies with limb presentation cannot be delivered safely via vaginal delivery. They must be delivered quickly by emergency C-section.

Limb presentation poses a large risk for dystocia, which is a medical emergency.

Occipitoposterior (OP) position

In occipitoposterior (OP) position, the baby is head-first with the back of the head turned towards the mother’s back. This position is also called an occiput posterior position. The baby’s head can be rotated to the right (right occipitoposterior position, or ROP), or to the left (left occipitoposterior position, or LOP).

Approximately 1 out of 19 babies present in a posterior position rather than an anterior position.

Occipitoposterior position increases the baby’s risk of experiencing:

prolonged labor
prolapsed umbilical cord
forceps and vacuum extractor injuries
brain bleeds
a lack of oxygen to the brain
Hypoxic-ischemic Encephalopathy (HIE)

If a manual rotation cannot be quickly and effectively performed in the face of fetal distress, the baby should be delivered via C-section. A C-section can help prevent oxygen deprivation caused by complications with OP position.

A nurse explains posterior position

Breech presentation

Breech presentation is normal throughout pregnancy. However, by the 37th week, the baby should change positions in time for labor. Breech presentation occurs when a baby’s buttocks or legs are positioned to descend the birth canal first. Breech positions are dangerous. During a vaginal delivery, a baby is at increased risk for serious problems with labor.

Most experts recommend C-section delivery for all types of breech positions because it is the safest method of delivery and it helps avoid birth injuries (6). Mismanaged breech birth can result in the following conditions:

Traumatic birth
brain bleeds (intracranial hemorrhages)
Spinal cord fractures
Hypoxic-ischemic encephalopathy (HIE)
Cerebral palsy
Intellectual disabilities
Developmental delays

Dealing with a birth injury can be difficult, but our attorneys can help.

Face presentation

A baby usually tucks its chin so they can be born head-first. A face presentation occurs when the face is the presenting part of the baby. In this position, the baby’s neck is extended backward. The back of the head touches the baby’s back. This prevents head engagement and descent of the baby through the birth canal.

In some cases of face presentation, the trauma of a vaginal delivery causes face deformation and fluid build-up (edema) in the face and upper airway. The baby will often need a breathing tube placed in the airway to maintain airway patency and assist breathing.

Image by healthhand.com

Trauma is very common during vaginal delivery of a baby in face presentation. Medical staff must warn parents that their baby may be bruised and that a C-section is available to avoid this trauma.

W hen face presentation occurs, experts recommend liberal use of C-section.

Complications of Mismanaged Face Presentation

Prolonged labor
Facial trauma
Facial and upper airway edema (fluid build-up in the face, often caused by trauma)
Skull molding (abnormal head shape that results from pressure on the baby’s head during childbirth)
Respiratory distress or difficulty in ventilation (the baby being able to move air in and out of lungs) due to upper airway trauma and edema
Spinal cord injury
Abnormal fetal heart rate patterns
10-fold increase in fetal compromise
Brain bleeds
Intracranial hemorrhages
Permanent brain damage

Brow presentation

Brow presentation is similar to face presentation, but the baby’s neck is less extended. A fetus in brow presentation has the chin untucked, and the neck is extended slightly backward. The brow (forehead) is the part situated to go through the pelvis first. Vaginal delivery can be difficult or impossible with brow presentation, because the diameter of the presenting part of the head may be too big to safely fit through the pelvis.

Risk factors and conditions associated with brow presentation

Brow presentation has been linked to several risk factors and co-occurring conditions. These include:

Multiparity (having previously given birth)
Premature delivery
anencephaly (an absence of major parts of the brain and skull)
anterior neck mass (a growth on the front of the neck)
Previous c-section delivery
Polyhydramnios (excessive amniotic fluid)

Diagnosis of brow presentation

Brow presentation can often be diagnosed through a vaginal examination during labor. If there are no conclusive signs from the physical examination, an ultrasound can show brow presentation.

Warning signs of brow presentation may include signs of fetal distress or lack of labor progression.

Management of brow presentation

Infants in brow presentation early in labor may spontaneously move into a safer position during the delivery process. Safe delivery in brow presentation may be possible if the infant is small and/or the mother’s pelvic opening is large. For these reasons, physicians occasionally recommend vaginal delivery of infants in brow presentation.

Doctors attempting vaginal delivery of a baby in brow presentation must watch for signs of fetal distress, such as an abnormal heart rate. Signs of fetal distress can indicate that a baby is in danger of sustaining serious brain injury. Quick intervention can prevent harm to the baby.

Medical staff should also monitor progression of labor when attempting a vaginal delivery of a baby in brow presentation. Prolonged labor can cause extended periods of fetal oxygen deprivation, which can cause birth asphyxia and permanent injury.

If an infant in brow presentation begins to show signs of distress, or if labor progress stops or slows significantly, physicians should be ready to move on to a cesarean delivery.

Labor induction or augmentation with the drug Pitocin (synthetic oxytocin) is very dangerous in cases of brow presentation. Pitocin can lead to excessive uterine contractions. The contractions can put pressure on the infant’s head and cut off their oxygen supply. In cases of brow presentation, usage of Pitocin is risky when the baby is not positioned for safe delivery.

Complications of brow presentation

Physicians can diagnose brow presentation early. When appropriately managed, delivery

can typically occur with no serious negative effects on the mother or baby.

However, if medical professionals fail to recognize brow presentation and intervene as necessary, there can be lasting consequences. Infants may suffer oxygen deprivation due to prolonged labor, or traumatic injuries from a difficult delivery. Some of the most severe conditions resulting from mismanaged brow presentation births include:

Hypoxic-ischemic encephalopathy
Periventricular leukomalacia
Seizure disorders
Developmental disabilities

Shoulder presentation (transverse lie)

Shoulder presentation (transverse lie) is when the arm, shoulder or trunk of the baby enter the birth canal first. When a baby is in a transverse lie position during labor, C-section is almost always used as the delivery method.

These situations make transverse lie position more likely:

polyhydramnios (too much amniotic fluid)
Multiples pregancy
placenta previa
a baby with intrauterine growth restriction (IUGR)

Once the membranes rupture, there is an increased risk of umbilical cord prolapse in this position. A C-section should ideally be performed before the membranes break. Failure to quickly deliver the baby by C-section when transverse lie presentation is present can cause severe birth asphyxia due to cord compression and trauma to the baby. This can cause hypoxic-ischemic encephalopathy (HIE), seizures, permanent brain damage, and cerebral palsy.

Legal help for birth injuries from abnormal position or presentation

The award-winning birth injury attorneys at ABC Law Centers: Birth Injury Lawyers have over 100 years of joint experience handling birth trauma cases related to abnormal position or presentation. If you believe your loved one’s birth injury resulted from an instance of medical malpractice, you may be entitled to compensation from a medical malpractice or personal injury case. During your free legal consultation, our birth injury attorneys will discuss your case with you, determine if negligence caused your loved one’s injuries, identify the negligent party, and discuss your legal options with you.

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Julien, S., and Galerneau, F. (2017). Face and brow presentations in labor. Retrieved from https://www.uptodate.com/contents/face-and-brow-presentations-in-labor .
World Health Organization, UNICEF, and United Nations Population Fund. Malpositions and malpresentations. Retrieved from http://hetv.org/resources/reproductive-health/impac/Symptoms/Malpositions__malpresetations_S69_S81.html .
Barth, W. (2016). Compound fetal presentation. Retrieved from https://www.uptodate.com/contents/compound-fetal-presentation .
Gabbe, S.G., … Grobman, W.A. (2017). Compound Presentation. Retrieved from https://expertconsult.inkling.com/read/gabbe-obstetrics-normal-problem-pregnancies-7e/chapter-17/compound-presentation .
Argani, C.H. and Satin, A.J. (2018) Occiput posterior position. Retrieved from https://www.uptodate.com/contents/occiput-posterior-position .
Hofmeyr, G.J. (2018). Overview of issues related to breech presentation. Retrieved from https://www.uptodate.com/contents/overview-of-issues-related-to-breech-presentation .
Hofmeyr, G.J. (2017). Delivery of the fetus in breech presentation. Retrieved from https://www.uptodate.com/contents/delivery-of-the-fetus-in-breech-presentation .
Strauss, R.A. (2017). Transverse fetal lie. Retrieved from https://www.uptodate.com/contents/transverse-fetal-lie .
Moldenhauer, J.S. (2018). Abnormal Position and Presentation of the Fetus. Retrieved from https://www.merckmanuals.com/home/women-s-health-issues/complications-of-labor-and-delivery/abnormal-position-and-presentation-of-the-fetus .

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Malpresentations and malpositions.

Published on 09/03/2015 by admin

Filed under Obstetrics & Gynecology

Last modified 09/03/2015

This article have been viewed 9632 times

Introduction

Malpresentation.

Malposition

During pregnancy, abdominal palpation should aim to define the lie, presentation and position of the fetus. The lie refers to the long axis of the fetus in relation to the long axis of the uterus. Usually, the fetus is longitudinal, but occasionally it may be transverse or oblique. The presentation is that part of the fetus which is at the pelvic brim, in other words the part of the fetus presenting to the pelvic inlet. Normal presentation is the vertex of the fetal head and the word ‘malpresentation’ describes any non-vertex presentation. This may be of the face, brow, breech, or some other part of the body if the lie is oblique or transverse.

The position of the fetus refers to the way in which the presenting part is positioned in relation to the maternal pelvis. Strictly speaking this refers to any presenting part, but here it will be considered in relation to those fetuses presenting head first (cephalic). As we have seen, the head is usually occipitotransverse at the pelvic brim and rotates to occipitoanterior at the pelvic floor. ‘Malposition’ is when the head, coming vertex first, does not rotate to occipitoanterior, presenting instead as persistent occipitotransverse or occipitoposterior.

As described above, ‘malpresentation’ is a term used to describe any non-vertex presentation. Over 95% of fetuses are in cephalic presentation at term. Malpresentations include face presentation, brow presentation and breech presentation. When the fetus has a cephalic presentation, the presenting diameter is dependent on the degree of flexion or extension of the fetal head – deflexed and brow presentations offer a wide diameter to the pelvic inlet ( Table 45.1 and Fig. 45.1 ).

Presenting diameters of the fetal head

Fig. 45.1 The presenting diameter is dependent on the degree of flexion or extension of the fetal head.

As the fetal skull is made up of individual bony plates (the occipital, sphenoid, temporal and ethmoid bones), which are joined by cartilaginous sutures (the frontal, sagittal, lambdoid and coronal sutures), it has the potential to be ‘moulded’ during labour. This allows the head to fit the birth canal more closely (Fig. 45.2) . Moulding should be distinguished from caput succedaneum, which refers to oedema of the presenting part of the scalp. Both moulding and caput can occur in any cephalic presentation, but are more likely to occur in malpresentation. The presence or absence of moulding and caput should be documented during each vaginal examination in labour; excessive moulding and caput are suggestive of an obstructed labour due to cephalopelvic disproportion.

Fig. 45.2 ‘Moulding’ refers to the change in shape of the fetal skull during labour as it ‘moulds’ to the birth canal.

Caput refers to oedema of the presenting part of the scalp.

Face presentation

This occurs in about 1:500 births and occurs when the fetal head extends right back (hyperextended so that the occiput touches the fetal back) (Fig. 45.3 A) . It is associated with prematurity, tumours of the fetal neck, loops of cord around the fetal neck, fetal macrosomia and anencephaly. Face presentation is usually only recognized after the onset of labour and, if the face is swollen (Fig. 45.3 B) , it is easy to confuse this presentation with that of a breech. The position of the face is described with reference to the chin, using the prefix ‘mento’. The presenting diameter is submentobregmatic (9.5 cm) (Fig. 45.1) .

Fig. 45.3 Face presentation.

(A) The head enters the pelvic brim in the transverse position. (B) Most rotate to the mentoanterior position and deliver without problems. (C) Those that rotate to mentoposterior will obstruct. (D) Face presentation is often associated with oedema and bruising. This baby recovered without problems.

The face usually enters the pelvis with the chin in the transverse position (mentotransverse) and 90% rotate to mentoanterior so that the head is born with flexion (Fig. 45.3 C) . If mentoposterior, the extending head presents an increasingly wider diameter to the pelvis, leading to worsening relative cephalopelvic disproportion and impacted obstruction (Fig. 45.3 D) . A caesarean section is usually required.

Brow presentation

This occurs in only approximately 1:700 and 1:1500 births and is the least favourable for delivery (Fig. 45.4) . The presenting diameter is mentovertical, measuring 14 cm. The supraorbital ridges and the bridge of the nose will be palpable on vaginal examination. The head may flex to become a vertex presentation or extend to a face presentation in early labour. If the brow presentation persists, a caesarean section will be required.

Fig. 45.4 Brow presentation.

Breech presentation

Breech presentation describes a fetus presenting bottom first. The incidence is around 40% at 20 weeks, 25% at 32 weeks and only 3–4% at term. The chance of a breech presentation turning spontaneously after 38 weeks is < 4%. Breech presentation is associated with multiple pregnancy, bicornuate uterus, fibroids, placenta praevia, polyhydramnios and oligohydramnios. It may also rarely be associated with fetal anomaly, particularly neural tube defects, neuromuscular disorders and autosomal trisomies. At term, 65% of breech presentations are frank (extended) with the remainder being flexed or footling (Fig. 45.5) . Footling breech carries a 5–20% risk of cord prolapse ( p. 367 ).

Fig. 45.5 Breech presentation.

Those presenting by the breech may be (A) extended (or frank); (B) flexed; or (C) footling.

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Sonographic evaluation of the fetal head position and attitude during labor

Introduction

Malposition, malpresentation, and asynclitism: toward a sonographic classification of labor dystocia?