On successfully completing this topic, you will be able to:
understand the mechanics of delivery of the baby presenting by the face
appreciate the importance of the positioning of the face in labour and prior to delivery
understand how to assess the situation when contemplating operative vaginal delivery.
Clinical approach
Diagnosis
Primary face presentation might be detected on a late ultrasound scan. The majority of face presentations are secondary and arise in labour.
Abdominal examination
A large amount of head is palpable on the same side as the back, without a cephalic prominence on the same side as the limbs, before the head has entered the pelvis.
Vaginal examination
In early labour, the presenting part will be high. At vaginal examination (VE), landmarks are the mouth, jaws, nose, malar and orbital ridges. The presence of alveolar margins distinguishes the mouth from the anus, so distinguishing a face presentation from that of a breech. In addition, the mouth and the maxillae form the corners of a triangle, while in a breech presentation, the anus is on a straight line between the ischial tuberosities.
During VE, avoid inadvertently damaging the eyes by trauma or antiseptics.
Management
Follow the steps:
make a diagnosis
check for cord presentation or prolapse
continuously monitor fetal heart rate
examine regularly to check that progress is adequate
give oxytocin if contractions are poor and progress is not satisfactory
do not use scalp electrodes or perform fetal blood sampling
if the position is mentoanterior, vaginal delivery should be possible (rotation from other positions can occur during labour)
if the fetus is persistently presenting mentoposteriorly, deliver by CS.
Intrapartum considerations
Labour in face presentation
In early labour, minor deflexion attitudes are common, especially with occipito-posterior positions and multiparity. In such cases, uterine contractions often cause increased flexion. Occasionally, extension will increase, producing successively a brow presentation and finally, the fully extended face. Most face presentations are thus secondary, becoming evident only in established labour. Diagnosis is notoriously difficult. In approximately 50% of cases the diagnosis is not made until delivery is imminent.
Descent is usually followed by internal rotation, with the chin passing anteriorly thus, as with other labours, progress is assessed by dilatation, rotation and descent. If contractions are inadequate, they can be augmented with oxytocin as long as signs of obstruction have been excluded.
It must be remembered that the biparietal diameter is 7 cm behind the advancing face, so that, even when the face is distending the vulva, the biparietal diameter has only just entered the pelvis. Descent is thus always less advanced than VE would suggest, even when one allows for the gross oedema that is usually present. The value of abdominal examination in such cases cannot be overstressed. However, when the chin is anterior and the occiput is posterior, it can be difficult to feel the fetal head abdominally even when it is still in the abdomen – ‘the head is always higher than you think with a face presentation’. The key is feeling posteriorly on vaginal examination – check the sacral hollow, which should be filled up by the occiput – if the sacral hollow is empty, the occiput is still intra-abdominal.
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