⚠️ Shoulder Dystocia — Overview
Shoulder dystocia occurs when the baby's head has been delivered but the anterior shoulder becomes impacted behind the maternal pubic symphysis, preventing further progress of delivery. It is an obstetric emergency requiring immediate structured management.
Time-critical emergency: Each minute of delay increases risk of foetal hypoxic-ischaemic injury and death. The brain can tolerate approximately 4–7 minutes of cord compression/hypoxia before irreversible damage occurs.
Incidence
- Complicates ~0.5–2% of vaginal deliveries
- Risk increases significantly with foetal macrosomia
Risk Factors
Antenatal Risk Factors
- Previous shoulder dystocia (10× recurrence risk)
- Foetal macrosomia (birthweight >4.0–4.5 kg)
- Maternal diabetes (gestational or pre-existing)
- Maternal obesity (BMI >30)
- Post-term pregnancy (>42 weeks)
- Maternal short stature / android pelvis
Intrapartum Risk Factors
- Prolonged first or second stage of labour
- Oxytocin augmentation
- Instrumental delivery (ventouse, forceps)
- "Turtle sign" — head retracts after delivery (like turtle retreating into shell)
- Failure of head to restitute
"Turtle sign": The delivered foetal head retracts back against the perineum after delivery (the head pulls back as the shoulder impacts the pubic symphysis). This is the diagnostic sign of shoulder dystocia.
Recognition
- Head delivers normally then fails to progress
- Turtle sign — head retracts toward perineum
- Chin retracts tightly against perineum
- Normal axial traction fails to deliver the shoulder
DO NOT apply fundal pressure (Kristeller) in shoulder dystocia — this impacts the shoulder further into the pelvis and worsens the obstruction.
🆘 HELPERR Mnemonic
HELPERR — Systematic management sequence for shoulder dystocia
H — CALL FOR HELP
Activate emergency call: additional midwife, senior obstetrician, paediatrician/neonatologist, anaesthetist. State: "Shoulder dystocia — help needed NOW." Note time of head delivery.
E — EVALUATE FOR EPISIOTOMY
Episiotomy does NOT relieve bony obstruction but may be needed to allow manoeuvres and hand placement. Consider if insufficient room.
L — LEGS (McRoberts Manoeuvre)
Hyperflexion of maternal thighs onto abdomen — flattens lumbar lordosis, rotates pubic symphysis superiorly, increases functional pelvic diameter. FIRST manoeuvre. Success rate ~40% alone.
P — SUPRAPUBIC PRESSURE
Downward pressure applied by assistant above pubic symphysis — directed to dislodge anterior shoulder from behind symphysis. NOT fundal pressure. Combine with McRoberts (L+P together = 54% success).
E — ENTER (Internal Rotational Manoeuvres)
Insert hand internally: Rubin II (push anterior shoulder toward foetal chest to reduce shoulder-to-shoulder diameter) or Woods Screw (push posterior shoulder forward). Combined = Rubin II + Woods Screw simultaneous.
R — REMOVE THE POSTERIOR ARM
Sweep the posterior arm across the foetal chest and deliver it. This reduces shoulder-to-shoulder diameter significantly. High success rate when other manoeuvres fail.
R — ROLL THE PATIENT (All-Fours)
Gaskin manoeuvre — turn patient onto hands and knees. Gravity may free impacted shoulder; sacrum becomes mobile. Can increase pelvic dimensions by up to 1–2 cm.
Last-resort manoeuvres (if all above fail):
- Zavanelli manoeuvre: replace baby's head into vagina → emergency caesarean
- Deliberate clavicle fracture (claviculotomy)
- Symphysiotomy (incision of symphysis pubis) — extreme last resort
🤲 Key Manoeuvres in Detail
McRoberts Manoeuvre (First-Line)
- Two assistants each hyperflexes one maternal thigh against abdomen
- Flattens lumbar lordosis → rotates symphysis pubis superiorly by ~12 degrees
- Increases subpubic space and facilitates shoulder dislodgement
- Alone: resolves ~40% of shoulder dystocia cases
- Combined with suprapubic pressure: resolves ~54%
Suprapubic Pressure
- Assistant applies firm downward-and-lateral pressure above symphysis pubis
- Direction: toward foetal face (to adduct the shoulder into the smaller oblique diameter of the pelvis)
- NOT fundal (Kristeller) pressure — Kristeller WORSENS impaction
- Can be continuous or with a rocking motion
Rubin II Internal Rotation
- Insert hand vaginally and push on the posterior aspect of the anterior shoulder
- Adducts the shoulder toward the foetal chest — reduces shoulder-to-shoulder (bisacromial) diameter
- Rotates shoulder complex into oblique diameter of pelvis (wider)
Woods Screw
- Place fingers on anterior aspect of posterior shoulder and push anteriorly
- Combines with Rubin II for corkscrew rotation
- Reverse Woods Screw (Rubin manoeuvre) rotates in opposite direction
Delivery of Posterior Arm
- Locate posterior arm in vagina → flex elbow → sweep arm across foetal chest → deliver hand → deliver posterior arm
- Reduces bisacromial diameter by the width of the arm (~20% reduction)
- High success rate when other manoeuvres unsuccessful
- Risk: humeral fracture (acceptable vs foetal death)
All-Fours Position (Gaskin Manoeuvre)
- Patient turned onto hands and knees mid-delivery
- Sacrum becomes mobile; posterior shoulder now becomes anterior and may fall free
- Gravity changes may dislodge impacted shoulder
- Effective but requires mobile patient (may be difficult with epidural)
Documentation after shoulder dystocia: Record time of head delivery, time baby fully delivered, all manoeuvres performed in sequence, personnel present, cord gases, Apgar scores, injuries to mother and baby. Debrief all involved staff.