Shoulder dystocia is a complication of vaginal cephalic delivery. It entails the inability to deliver the body of the fetus using gentle traction, the head having already been delivered. It usually occurs due to impaction of the anterior fetal shoulder on the maternal pubic symphysis. Shoulder dystocia is a cause of both maternal and fetal morbidity.

Key risk factors

• fetal macrosomia (hence association with maternal diabetes mellitus)
• high maternal body mass index
• diabetes mellitus
• prolonged labour

Management

Senior help should be called as soon as shoulder dystocia is identified and McRoberts' manoeuvre should be performed:

• this manoeuvre entails flexion and abduction of the maternal hips, bringing the mother's thighs towards her abdomen
• this rotation increases the relative anterior-posterior angle of the pelvis and often facilitates a successful delivery.

An episiotomy will not relieve the bony obstruction but is sometimes used to allow better access for internal manoeuvres. Symphysiotomy and the Zavanelli manoeuvre can cause significant maternal morbidity and are not first-line options. Oxytocin administration is not indicated in shoulder dystocia.

Complications

Potential complications include:

• maternal
  • postpartum haemorrhage
  • perineal tears
• fetal
  • brachial plexus injury
  • neonatal death