Persistent Occiput Posterior Position

Persistent occiput posterior position is a fetal head that stays with the occiput toward the maternal sacrum throughout labour, instead of rotating to occiput anterior. Many babies are occiput posterior at the start of labour, and fewer at birth. It results from a flat posterior pelvis, a deflexed head, anterior placenta, weak contractions and epidural. It matters because it causes severe back pain, a long labour, assisted delivery, caesarean section and severe perineal tears.

• Risk factors: first labour, previous occiput posterior birth, obesity, android or anthropoid pelvis, anterior placenta, epidural, maternal age above 35 years.
• Most rotate spontaneously during labour.
• Birth is possible face to pubes with a larger diameter and more trauma.

Women have severe backache that does not ease between contractions, an early urge to push, slow progress and early membrane rupture. Abdominal examination shows a flat or hollow lower abdomen with fetal limbs palpable at the front and the fetal heart heard at the flank.

• Backache and an early urge to push before full dilatation.
• Anterior fontanelle felt in front on vaginal examination.
• Differential diagnosis: occiput transverse position, deflexed vertex, face or brow presentation, cephalopelvic disproportion, abruption, uterine rupture, urinary infection.
• Complications: prolonged labour, obstructed labour, maternal exhaustion, assisted delivery, caesarean section, third and fourth degree tears, postpartum haemorrhage, birth trauma.

The diagnosis is by abdominal and vaginal examination with ultrasound confirmation.

• Abdominal examination: back not felt at the front, limbs felt anteriorly, fetal heart at the flank.
• Vaginal examination: posterior fontanelle (Y shaped) toward the sacrum, anterior fontanelle (diamond shaped) toward the pubis, ears for confirmation, station and degree of flexion.
• Ultrasound (transabdominal) for position: spine toward the maternal spine and orbits toward the pubis.
• Cardiotocography; maternal pulse, temperature, hydration; estimated fetal weight; pelvic assessment.

The principle is analgesia, hydration, maternal positions that encourage rotation and, when needed, oxytocin, manual rotation or assisted delivery.

• Supportive: hands and knees, lateral and upright positions; pelvic tilt and counter pressure on the back; empty the bladder; Ringer's lactate 1 litre IV over 1 to 2 hours; warm shower or bath; one to one support; analgesia (epidural or pethidine 50 to 100 mg IM 4-hourly, maximum 400 mg in 24 hours); continuous cardiotocography on oxytocin.
• Pharmacological:
  • Weak contractions without disproportion: oxytocin 10 IU in 1 litre Ringer's lactate (10 mU/mL) started at 12 mL per hour (2 mU/minute) and doubled every 30 minutes to a maximum of 192 mL per hour (32 mU/minute).
  • Perineal infiltration: lignocaine 1 percent 10 to 20 mL (maximum 3 mg/kg, not above 200 mg).
  • Amoxicillin-clavulanate 1.2 g IV as a single dose after operative vaginal delivery.
  • Amoxicillin-clavulanate 625 mg oral 8-hourly for 5 days for third or fourth degree tears.
  • Cefazolin 2 g IV before caesarean section.
  • Oxytocin 10 IU IM after birth, then 20 IU in 1 litre at 125 mL per hour for 4 hours.
  • Tranexamic acid 1 g IV over 10 minutes if bleeding exceeds 500 mL.
• Procedures: amniotomy when the head is engaged; manual rotation to occiput anterior at full dilatation; vacuum or forceps delivery face to pubes (occiput posterior) or after rotation (occiput anterior); episiotomy when needed; caesarean section for obstruction, failed assisted delivery or fetal compromise.
• Special groups: epidural analgesia allows an extra hour for rotation and descent; a uterine scar uses oxytocin only with senior review and continuous monitoring.
• Red flags: abnormal fetal heart rate, thick meconium, bandl ring, scar tenderness, fever above 38 degrees Celsius, bleeding, maternal exhaustion.
• Follow-up: bladder catheter for 24 hours after assisted birth; examine for sphincter injury; review at 1 week and 6 weeks; counselling that recurrence is common.