Shoulder Dystocia

Shoulder dystocia is failure of the fetal shoulders to deliver after the head, because the anterior shoulder is impacted behind the maternal pubic symphysis, and the delivery needs extra manoeuvres. It cannot be predicted reliably. It matters because the fetus can suffer brachial plexus injury, clavicle or humerus fracture, hypoxia and death, and the mother suffers severe perineal tears and postpartum haemorrhage.

• Risk factors: macrosomia (above 4000 g), maternal diabetes, previous shoulder dystocia, obesity, post term pregnancy, prolonged second stage, assisted vaginal delivery.
• Many cases occur in babies weighing below 4000 g.
• Hypoxic injury can begin within minutes of the head delivering.

After the head is born it retracts against the perineum (turtle sign), and the chin does not release and the shoulders fail to deliver with routine downward traction. The baby's face may be congested.

• Head delivers with difficulty and pulls back against the perineum.
• No restitution or rotation of the head.
• Differential diagnosis: tight nuchal cord, short cord, locked twins, fetal neck mass, abnormal fetal anatomy, sacrococcygeal teratoma.
• Complications: brachial plexus injury (Erb palsy), clavicle fracture, humeral fracture, neonatal hypoxia and encephalopathy, fetal death, third and fourth degree tears, postpartum haemorrhage, uterine rupture, maternal psychological injury.

The diagnosis is clinical and made at birth when the shoulders do not deliver with routine traction.

• Record the time the head delivered, each manoeuvre used, the time of delivery of the body, and the position of the fetal back.
• Cardiotocography showing prolonged deceleration after the head delivers.
• Antenatal assessment of risk: estimated fetal weight, glucose tolerance test, previous history.
• After birth: baby's Apgar score, arms for movement, clavicles and humeri for fracture; umbilical cord blood gas.

The principle is to call for help at once and use a fixed sequence of manoeuvres without fundal pressure or excessive traction.

• Supportive: call for help (senior obstetrician, anaesthetist, neonatal team) and note the time; stop the mother pushing; lay the mother flat with the buttocks at the edge of the bed; empty the bladder; do not pull on the head or apply fundal pressure; explain to the mother.
• Pharmacological: lignocaine 1 percent 10 to 20 mL (maximum 3 mg/kg, not above 200 mg) for episiotomy if needed; oxytocin 10 IU IM after the shoulders are delivered, then 20 IU in 1 litre Ringer's lactate at 125 mL per hour for 4 hours; tranexamic acid 1 g IV over 10 minutes if bleeding exceeds 500 mL; amoxicillin-clavulanate 1.2 g IV as a single dose then 625 mg oral 8-hourly for 5 days for third or fourth degree tears; paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours); newborn vitamin K 1 mg IM and resuscitation with bag and mask if not breathing.
• Procedures: McRoberts position (hyperflex both hips onto the abdomen) with routine axial traction; suprapubic pressure (continuous or rocking, from the side of the fetal back, directed to push the shoulder across) for 30 to 60 seconds; episiotomy only if it helps internal manoeuvres; delivery of the posterior arm (hand into the sacral hollow, flex the elbow, sweep the forearm over the chest); internal rotational manoeuvres (Rubin and Woods screw) with a hand behind the shoulder; all fours position (Gaskin) with downward traction of the posterior shoulder; cleidotomy, symphysiotomy or Zavanelli manoeuvre (replacement of the head with caesarean section) only as last resorts by experienced operators.
• Special groups: women with diabetes have the newborn feed within 30 minutes and have glucose checked at 2 hours, with glucose below 2.6 mmol/L treated by dextrose 10 percent 2 mL/kg IV over 10 minutes then 80 mL/kg per day; women with a previous shoulder dystocia are offered elective caesarean section because the recurrence risk is raised.
• Red flags: head to body interval above 5 minutes, fetal bradycardia, flat or floppy baby, bleeding above 500 mL, third or fourth degree tear.
• Follow-up: newborn examination of the arm and clavicle within 24 hours; physiotherapy and specialist review if arm weakness persists at 3 months; debrief and written record; maternal perineal care and review at 6 weeks.