Face and brow presentations in labor

INTRODUCTION — The vast majority of fetuses at term are in cephalic presentation. Approximately 5 percent of these fetuses are in a cephalic malpresentation, such as occiput posterior or transverse, face (figure 1A-B), or brow (figure 2) [1].

Diagnosis and management of face and brow presentations will be reviewed here. Other cephalic malpresentations are discussed separately. (See "Occiput posterior position" and "Occiput transverse position".)

OVERVIEW

Prevalence — Face and brow presentation are uncommon. Their prevalences compared with other types of malpresentations are shown below [1-9]:

●Occiput posterior – 1/19 deliveries

●Breech – 1/33 deliveries

●Face – 1/600 to 1/800 deliveries

●Brow – 1/500 to 1/4000 deliveries

●Transverse lie – 1/833 deliveries

●Compound – 1/1500 deliveries

The prevalence of face presentation at Parkland Memorial Hospital in Texas (United States) has decreased to 1/2000 deliveries in recent years [10], possibly because of fewer deliveries of fetuses with anomalies such as anencephaly [11,12]; however, others have not observed a decline [9,12,13].

Clinical significance — During labor in the occiput anterior presentation, the neck normally flexes to bring the chin to the chest, resulting in the relatively small suboccipito-bregmatic diameter (average length 9.5 cm) as the widest cephalic diameter that needs to negotiate the pelvis. This diameter is generally able to traverse the obstetric conjugate (average length 10.5 cm) (figure 3), which is the shortest anteroposterior pelvic diameter. By comparison, the neck is extended in brow and face presentations, which present larger fetal cephalic diameters that need to negotiate the pelvis (figure 4). Thus, protraction or arrest of descent is more likely, which increases the chances of maternal and neonatal morbidity from vaginal birth and the frequency for cesarean birth. Brow and mentum posterior face presentations are most likely to exhibit cephalopelvic dystocia unless the fetus is very small or the maternal pelvis is very large or both. (See 'Neonatal outcome' below and 'Neonatal outcome' below.)

Fetal heart rate abnormalities are more common than with occiput anterior position [2,14]. They may be due to more head compression or a higher frequency of cord compression.

Risk factors — Maternal or fetal anatomic factors that prevent flexion or favor extension of the fetal neck increase the risk for face/brow presentation. These factors include anencephaly, severe hydrocephalus with cephalomegaly, anterior neck mass, multiple nuchal cords, cephalopelvic disproportion, preterm birth/low birth weight, macrosomia, contracted maternal pelvis, platypelloid pelvis (figure 5), multiparity, polyhydramnios, previous cesarean birth, and Black race [2,5,8,9,11-13].

In multiparous patients, poor abdominal muscle tone may permit the uterine fundus and fetal trunk to swing anteriorly, which may extend the cervical spine, leading to a face or brow presentation [13]. Alternatively, late engagement of the vertex in multiparous patients, often after the onset of labor, may be the predisposing factor [12].

A contracted maternal pelvis predisposes to malpresentation [12]. The increased risk of face/brow presentation in Black patients may be due to differences in pelvic dimensions between White and Black females and a higher rate of preterm birth in Black individuals [13,15-17]. The differences in pelvic dimensions may be related to environmental differences (eg, locomotion, load carrying, health, nutrition) [18].

Although preterm birth has been linked to face/brow presentation, possibly because a very small fetus can descend with the neck partially extended, the association between preterm birth and face presentation is weak [9,13].

Pregnancies with polyhydramnios may be at risk secondary to impaired swallowing due to a fetal anomaly (particularly anencephaly) [12] or to obstruction of the fetal trachea and esophagus from a hyperextended fetal neck [5].

FACE PRESENTATION

Definition — Face presentation refers to a fetal presentation in which the fetal face from forehead to chin is the leading fetal body part descending into the birth canal (figure 1B). The fetal neck is highly extended (sharply deflexed), such that the occiput may touch the back.

Diagnosis — The intrapartum diagnosis of face presentation is made by vaginal examination in the late first or the second stage of labor [5]. Palpation of the orbital ridge and orbits, saddle of the nose, mouth, and chin is diagnostic of face presentation. The fontanelles and sutures are not generally palpable [19]. At diagnosis, nearly 60 percent of face presentations are mentum anterior, 26 percent are mentum posterior, and 15 percent are mentum transverse, and may be designated as left or right (figure 1A) [11].

Intrapartum transabdominal, translabial, and/or transvaginal sonography of a face presentation will show a hyperextended fetal neck, with the orbits and nasal bridge at the center of the presenting part in the mid-sagittal plane [20]. Although imaging studies can be performed to confirm the diagnosis if it is uncertain, imaging is not mandatory, and results do not have prognostic value for predicting the outcome of labor [21].

Differential diagnosis — Face presentation may be misdiagnosed as a frank breech presentation on digital examination since the latter is more commonly encountered (and therefore expected). Both presentations are characterized by soft tissues with an orifice; however, careful palpation will identify the bony facial structures and lead to the correct diagnosis. With ultrasound readily available in most delivery units, confirmation of the type of malpresentation (breech or face) is easily obtained if needed.

Labor and delivery management

Fetal heart rate monitoring — The fetal heart rate is monitored continuously, ideally with an external device. An internal device may cause facial or ophthalmic injuries if improperly placed [22-24]. If internal monitoring is required, the electrode should be carefully applied over a bony structure such as the forehead, mandible, or zygomatic bones to minimize the risk of trauma [25].

Abnormalities of the fetal heart rate occur more frequently with face presentations [4,25,26]. In one series, severe variable and late decelerations developed in 29 and 24 percent of labors, respectively [25]. Only 14 percent of pregnancies had normal tracings. Moreover, 13 percent of the newborns had a low five-minute Apgar score.

Interpretation and management of abnormal fetal heart rate tracings are not affected by fetal presentation and are reviewed separately. We perform amnioinfusion for patients with variable decelerations (category 2 tracing), regardless of presentation, as long as vaginal birth is anticipated. (See "Intrapartum category I, II, and III fetal heart rate tracings: Management".)

Mentum anterior — In mentum anterior face presentation, the fetal chin needs to pass under the symphysis pubis. For this to occur, the extended fetal neck may need to extend even more. After the chin clears the symphysis, further descent and fetal expulsion can occur [5]. Over 75 percent of mentum anterior fetuses are born vaginally [2,3,13,26,27].

The parturient may begin pushing at full dilation. Labor progress should be closely monitored as arrest of descent may occur, although not inevitably as in persistent mentum posterior position.

Oxytocin augmentation and cesarean birth are performed for standard obstetric indications [26]. (See "Labor: Overview of normal and abnormal progression".)

Attempts at version or vacuum- or midforceps-assisted delivery should be avoided as they are associated with unnecessary maternal trauma and neonatal injury [28].

An outlet forceps-assisted delivery when the face is distending the perineum is not contraindicated if delivery must be facilitated but should only be performed by experienced clinicians familiar with the particular considerations involved. For example, in contrast to the occiput anterior position, engagement does not occur until the face is at +2 station [5]; the chin rather than the occiput is the focal point for orientation; and if Kielland forceps are applied, the left blade is applied to the right side of the head and the right blade to the left side [29,30]. The technique of forceps delivery is beyond the scope of this review.

Mentum posterior — In the mentum posterior face presentation, the fetal neck is already maximally extended and cannot extend further to allow the occiput to pass under the symphysis. Therefore, the mentum posterior face presentation will not deliver vaginally unless spontaneous rotation to mentum anterior occurs (figure 6), often late in the second stage of labor [14], or the fetus is very small, or the pelvis is very large. If the fetal status is reassuring and there is normal labor progress, mentum posterior presentation can be managed expectantly to see if spontaneous rotation will occur [14].

Patients with abnormal labor progression are delivered by cesarean. We individualize management when labor is progressing. For example, in multiparous patients with an adequate pelvis and fetus estimated to weigh less than their prior newborns, we would follow labor progress closely and maintain a low threshold for abandoning attempts at vaginal birth if labor does not progress normally in the first or second stage. However, if the fetus is estimated to be larger than their prior newborns, or in nulliparous patients, we would recommend cesarean birth early in the labor course. There is consensus that assisted vaginal delivery is contraindicated for mentum posterior presentations [14,31,32].

In the past, manual version of the mentum posterior face to an occiput anterior or mentum anterior position was attempted using internal and external manipulation [33,34]. Although some clinicians have been successful with no serious neonatal or maternal complications, others have reported maternal deaths from uterine rupture, cord prolapse resulting in neonatal asphyxia, and cervical spine trauma resulting in severe neonatal neurologic sequelae [28]. Given the safety and ready availability of cesarean birth, we believe internal version should be reserved for occasions when cesarean birth is unable to be accomplished due to lack of surgical facilities and inability to arrange maternal transport, or absolute maternal refusal to allow a cesarean birth [34].

Mentum transverse — There are minimal published data on management of the mentum transverse position. Our management is the same as for mentum posterior.

Neonatal outcome — Prior to 1955, increased rates of intrapartum fetal death and perinatal mortality (approximately 10 percent) were reported for face presentation [5]. Perinatal mortality decreased to 2 to 3 percent by 1980, likely due to the increased use of cesarean birth, as well as other advances in obstetric and neonatal care [5]. Recent perinatal mortality data are not available.

Neonates who were in face presentation often have significant facial edema, facial bruising/ecchymosis, and skull molding [35]. This usually resolves within the first 24 to 48 hours of life. Personnel and equipment for performing endotracheal intubation should be readily available at birth [25]. Difficulty in ventilation during resuscitation has been reported and attributed to tracheal and laryngeal trauma and edema.

Facial trauma and spinal cord injury have also been described in case reports and are often associated with version, extraction, and midforceps rotations [2,23-25,36]. Appropriate management of face presentation, as described above, typically does not result in increased serious maternal or neonatal morbidity [2].

BROW PRESENTATION

Definition — Brow presentation refers to a presentation in which the fetal surface presenting in the birth canal extends from the anterior fontanelle to the brow (orbital ridge), but does not include the mouth and chin (figure 2). The fetal neck is extended, but not to the degree of a face presentation.

Diagnosis — The diagnosis of brow presentation is made by vaginal examination in the second stage of labor [5]. Palpation of the forehead, orbital ridge, orbits, and saddle of the nose, but not the mouth and chin, is diagnostic of brow presentation. The anterior fontanelle is palpable, but the sagittal suture generally is not [19]. The brow may be anterior or posterior and described by the position or the anterior fontanelle as frontal anterior, transverse, or posterior [14].

There is increasing evidence that ultrasound is more accurate than vaginal examination for determining fetal position and can be used to determine or confirm abnormal presentation [37,38]. On transabdominal examination, if the occiput is anterior, the main finding is a reduction in occiput-spinal angle, usually around 90 degrees rather than over 120 degrees; if the occiput is posterior, the chin is separate from chest, and the cervical spine is curved (convex) anteriorly [19]. If a transperineal examination is performed, the fetal orbits are seen at the same level as the pubic symphysis.

Labor and delivery management — The fetal heart rate is monitored continuously during labor, ideally with an external device, since fetal heart rate abnormalities are more common than with occiput anterior position. An internal device may cause facial or ophthalmic injuries if improperly placed [22-24]. If internal monitoring is required, the electrode should be cautiously applied over a bony structure, such as the forehead, to minimize the risk of trauma [25].

Patients with a clinically adequate or proven pelvis can undergo a trial of labor since many brow presentations are transitional. In one review, when brow presentation was diagnosed early in labor, 67 to 75 percent of fetuses spontaneously converted to a more favorable presentation and delivered vaginally. When diagnosed late in labor, 50 percent spontaneously converted and delivered vaginally: in 30 percent, the neck extended further resulting in mentum anterior face presentation; in 20 percent, the neck flexed resulting in an occiput posterior presentation [2,5,39]. Conversion to occiput anterior is rare.

If the brow presentation persists, labor progress is usually protracted or arrests, necessitating cesarean birth. Oxytocin augmentation is not recommended in this setting, given the association between brow presentation and cephalopelvic disproportion [5,26,33]. Version or vacuum- or forceps-assisted delivery are not recommended, as the risks for maternal and fetal injury are high [5,14,31,32]. However, in settings where cesarean birth is not readily available, vacuum-assisted flexion of the fetal head may be considered [40].

In a minority of cases, spontaneous vaginal birth may be possible if the fetus is extremely small or macerated or the maternal pelvis is unusually large.

Neonatal outcome — Recognition and appropriate management of brow presentation, as described above, typically do not result in increased serious maternal or neonatal morbidity.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Labor".)

SUMMARY AND RECOMMENDATIONS

Issues common to face and brow presentations

●Risk factors – Face and brow presentations are associated with multiparity, cephalopelvic disproportion, preterm birth, polyhydramnios, and fetal anomalies (eg, anencephaly, anterior neck mass). (See 'Risk factors' above.)

●Clinical significance – The deflexed neck in face or brow presentation inhibits head engagement and subsequent fetal descent. (See 'Clinical significance' above.)

●Cautions – The fetal heart rate is monitored continuously during labor, ideally with an external device, because of the increased prevalence of fetal heart rate decelerations. An internal device may cause facial or ophthalmic injuries if improperly placed. If internal monitoring is required, the electrode should be carefully applied over a bony structure to minimize the risk of trauma. (See 'Labor and delivery management' above.)

Face

●Definition – In face presentation, the fetal face from forehead to chin is the leading fetal body part descending into the birth canal (figure 1B). The fetal neck is sharply deflexed and the occiput may touch the back. Nearly 60 percent of face presentations are mentum anterior, 26 percent are mentum posterior, and 15 percent are mentum transverse, and may be designated as left or right (figure 1A). (See 'Definition' above.)

●Diagnosis – The diagnosis of face presentation is made by vaginal examination. Palpation of the orbital ridge and orbits, saddle of the nose, mouth, and chin is diagnostic of face presentation (figure 1A). Ultrasound can be used to confirm or clarify the type of malpresentation if the clinical examination findings are unclear. (See 'Diagnosis' above.)

●Management

•Mentum anterior – Over 75 percent of mentum anterior fetuses deliver vaginally; this rate is similar to that for all fetuses in cephalic presentations. For face presentation with the mentum anterior, we suggest a trial of labor rather than cesarean birth (Grade 2C). Oxytocin augmentation may be administered in the setting of a normal fetus with protracted labor, as long as the fetal heart rate pattern remains reassuring. (See 'Labor and delivery management' above.)

•Mentum posterior – The mentum posterior face presentation will not deliver vaginally unless spontaneous rotation occurs, which is infrequent and occurs late in the second stage of labor, or the fetus is very small or the pelvis very large or both. As mentum posterior presentations are rare, we individualize management of such situations. In a multiparous patient with an adequate pelvis and fetus estimated to weigh less than her prior newborns, we follow labor progress closely and maintain a low threshold for abandoning attempts at vaginal birth if labor does not progress normally in the first or second stage. We recommend cesarean birth rather than manual rotation (Grade 1C).

If the fetus is estimated to be larger than the patient’s prior newborns or the patient is nulliparous, we perform cesarean birth early in the labor course. (See 'Labor and delivery management' above.)

Brow

●Definition – In brow presentation, the fetal surface presenting in the birth canal extends from the anterior fontanelle to the brow (orbital ridge), but does not include the mouth and chin (figure 2). The fetal neck is extended, but not to the degree of a face presentation. (See 'Definition' above.)

●Diagnosis – The diagnosis of brow presentation is made by vaginal examination. Palpation of the forehead, orbital ridge, orbits, and saddle of the nose, but not the mouth and chin, is diagnostic of brow presentation (figure 2). Ultrasound can be used to confirm or clarify the type of malpresentation if the clinical examination findings are unclear. (See 'Diagnosis' above.)

●Management – Patients with a fetus in brow presentation and a clinically adequate or proven pelvis can undergo a trial of labor, with close monitoring and delivery by cesarean for standard indications. The brow presentation is often a transitional state: 50 percent will spontaneously convert to a face or occipital presentation. Fetuses with persistent brow presentation should be delivered by cesarean since vaginal birth is not possible unless the fetus is very small, the pelvis is very large, or both. Operative vaginal delivery is contraindicated for brow presentation. (See 'Labor and delivery management' above.)