Shoulder dystocia

• Overview:

  • Complication of vaginal cephalic delivery when the anterior fetal shoulder becomes stuck on the maternal pubic symphysis - resulting in delayed birth of the baby's body
  • Obstetric emergency - risk of hypoxic brain injury for the baby
• Pathophysiology:

  • Baby's head is delivered but the shoulders prevent progression
  • The shoulders are only just reaching the pelvic floor, therefore they are still negotiating the pelvic outlet
  • Shoulder compression may cause the umbilical cord to become compressed between the baby's body and the mother's pelvis or the baby's neck may be compressed at an angle that limits blood flow
  • Interruption of the oxygen supply may cause hypoxic brain injury - greater risk the longer baby is trapped
• Pre-labour risk factors for shoulder dystocia:

  • Previous shoulder dystocia
  • Macrosomia >4.5kg
  • Diabetes mellitus
  • Maternal BMI >30
  • Induction of labour
• Intrapartum risk factors for shoulder dystocia:

  • prolonged first stage of labour
  • Secondary arrest - no change in cervical dilation over time
  • Prolonged second stage of labour
  • Oxytocin augmentation
  • Assisted vaginal delivery
• If a woman has diabetes the risk is significantly higher even with a similar-sized baby. If a woman has pre-existing diabetes or develops diabetes in pregnancy, they will usually be offered early labour induction or a planned caesarean to reduce/eliminate the risk of shoulder dystocia.
• Typical signs during delivery:

  • Slower delivery of the head
  • Unable to deliver the anterior shoulder after the delivery of the head with the next contraction
  • Turtleneck sign - the appearance and retraction of the baby's head, with a red puffy face
• Initial management:

  • Call for help
  • Advise mother to stop pushing
  • McRoberts manoeuvres (first line) - hyperflex maternal hips to widen pelvic outlet, this alone has a success rate of 90%, which is even higher when combined with suprapubic pressure - applied behind the anterior shoulder to disimpact it from the maternal symphysis
• Second line internal manoeuvres:

  • Posterior arm - inserting the hand posteriorly to grasp the posterior fetal arm and deliver
  • Internal rotation (corkscrew) - simultaneously applying pressure in front of one shoulder and behind the other - aim is to rotate the baby 180 degrees
• An episiotomy can allow more space to facilitate internal vaginal manoeuvres but will not relieve the bony obstruction of the shoulder. The use of an episiotomy will not decrease the risk of brachial plexus injury.
• Always avoid downwards traction on the fetal head as this increases the risk of brachial plexus injury.
• Zavanelli manoeuver involves pushing the baby’s head back into the vagina so that the baby can be delivered by emergency caesarean section.
• Post delivery management:

  • Active management of the third stage of labour is recommended due to the increased risk of post-partum haemorrhage
  • Can be a traumatic experience for the mother and birth partner - support and debrief following delivery
  • Rectal examination should be performed to exclude a third or fourth degree tear
  • Paediatric review before discharge to assess for complications such as brachial plexus injury
• Maternal complications of shoulder dystocia include:

  • Third- or fourth-degree tears
  • Post-partum haemorrhage
  • Trauma/post-traumatic stress disorder
• Foetal complications of shoulder dystocia include:

  • Brachial plexus injury (BPI)
  • Fractures: humerus or clavicle
  • Hypoxic brain injury.
• Brachial plexus injury:

  • Around 1 in 10 babies who have shoulder dystocia will have a degree of stretching of the brachial nerve plexus in the neck
  • Most common type is Erb's palsy - usually temporary and movement will return without hours or days. Permanent damage is rare
  • Arm hanging limply from the shoulder - adduction at the shoulder, internal rotation of the upper arm, pronation of the forearm, outward direction of the palm - waiter's tip posture
  • Grasp reflex is present