Shoulder Dystocia

An obstetric emergency in which, after delivery of the fetal head, the anterior fetal shoulder impacts against the maternal symphysis pubis (or, less commonly, the posterior shoulder against the sacral promontory), preventing further spontaneous descent.

Risk factors include macrosomia (though the majority of cases occur in normally grown fetuses, making it largely unpredictable), maternal diabetes, previous shoulder dystocia, prolonged first or second stage, and instrumental delivery, but shoulder dystocia frequently occurs without any identifiable risk factor, meaning all birth attendants must be prepared to manage it at any delivery.

The classic "turtle sign", the fetal head retracts back against the perineum immediately after delivery, rather than the normal external restitution and gentle descent, is the hallmark recognition sign.

Failure of the anterior shoulder to deliver with routine gentle downward traction confirms the diagnosis.

Clinical, made at the moment of delivery.

Time from delivery of the head to delivery of the body is critical, given the risk of fetal hypoxia from cord compression within the birth canal and, in severe or prolonged cases, brachial plexus injury from excessive traction.

Follows a structured, stepwise algorithm, commonly remembered as HELPERR, executed promptly and without delay:

• Call for Help: senior obstetrician, senior midwife, anesthetist, neonatal team, all summoned immediately

• Evaluate for episiotomy: performed if needed to create space for internal maneuvers, not to relieve the bony obstruction itself

• Legs: McRoberts maneuver, hyperflexing the maternal hips onto the abdomen, straightens the lumbosacral angle and rotates the symphysis, resolving a significant proportion of cases alone

• Pressure: suprapubic pressure, applied by an assistant in a downward and lateral direction over the anterior shoulder, combined with continued McRoberts positioning and gentle traction

• Enter the pelvis (internal maneuvers): Rubin II (pressure on the posterior aspect of the anterior shoulder to adduct and rotate it under the symphysis) or Woods' screw maneuver (rotating the posterior shoulder progressively to displace and deliver the anterior shoulder)

• Remove the posterior arm: delivering the posterior arm first, flexing the fetal elbow and sweeping the arm across the chest, effectively reduces the bisacromial diameter and often resolves the dystocia

• Roll the patient: onto all fours (Gaskin maneuver), which can alter pelvic dimensions and facilitate delivery, particularly useful where other maneuvers have failed or in settings without immediate access to internal maneuvers expertise

Avoid excessive traction on the fetal head, fundal pressure (which worsens impaction rather than relieving it), and excessive lateral flexion of the head, all of which increase the risk of brachial plexus injury and other birth trauma.

• After delivery, thorough examination of the neonate for brachial plexus injury (Erb's palsy) and clavicular or humeral fracture, and of the mother for perineal or vaginal trauma and postpartum hemorrhage (see that entry), given the significantly elevated PPH risk following shoulder dystocia

• Careful, contemporaneous documentation of the sequence of maneuvers used and timings, given the medicolegal significance of shoulder dystocia events

Referral: neonatal team assessment for all cases; ongoing follow-up for confirmed brachial plexus injury.