Shoulder Dystocia

Definition

• Shoulder dystocia is a vaginal cephalic delivery that requires additional obstetric manoeuvres to deliver the fetal shoulders after gentle downward traction has failed
• The anterior shoulder impacts behind the maternal symphysis pubis (or less commonly, the posterior shoulder on the sacral promontory)
• Incidence: 0.6-0.7% of all vaginal deliveries
• "Head-to-body" delivery interval >60 seconds is a practical marker

Risk Factors

Antenatal

• Previous shoulder dystocia (recurrence risk 1-25%)
• Fetal macrosomia (>4000g, especially >4500g)
• Maternal diabetes (gestational or pre-existing) — independent risk factor beyond macrosomia alone
• Maternal BMI >30
• Post-dates pregnancy (>42 weeks)
• Previous macrosomic infant

Intrapartum

• Prolonged first stage of labour
• Prolonged second stage of labour
• Augmented labour (oxytocin)
• Instrumental vaginal delivery (particularly mid-cavity)
• Secondary arrest in labour

Limitations of Prediction

• 50% of shoulder dystocia cases occur in infants <4000g
• 98% of macrosomic infants are delivered without shoulder dystocia
• No reliable predictive model exists — all birth attendants must be trained in management

Management: HELPERR Mnemonic

1. H — Help: call for senior obstetrician, additional midwife, anaesthetist, neonatologist. Note the time.
2. E — Evaluate for Episiotomy: episiotomy does not relieve bony obstruction but may provide space for internal manoeuvres
3. L — Legs (McRoberts position): hyperflexion of maternal thighs onto abdomen. Flattens lumbar lordosis, increases AP diameter of pelvis by 1-2cm. Successful in 40-90% of cases.
4. P — Pressure (suprapubic): continuous or rocking pressure applied above the pubic symphysis, directed posteriorly and laterally to reduce the anterior shoulder diameter. Applied by assistant while operator applies routine axial traction. Do NOT apply fundal pressure (risk of uterine rupture).
5. E — Enter (internal manoeuvres):
   • Rubin II manoeuvre: fingers behind the anterior shoulder, push it towards the fetal chest (adduct) to reduce the bisacromial diameter
   • Wood's screw manoeuvre: pressure on the anterior aspect of the posterior shoulder to rotate the fetus 180 degrees, disimpacting the anterior shoulder
   • Reverse Wood's screw: combined pressure on both shoulders in opposite directions
6. R — Remove the posterior arm: reach in, flex the posterior elbow, sweep the forearm across the chest and deliver. Reduces the bisacromial diameter by the width of the arm (~20%). May cause humeral fracture but this heals well.
7. R — Roll the patient (all-fours position/Gaskin manoeuvre): patient on hands and knees. Utilises gravity and changes pelvic diameters. Can be difficult with epidural.

Last Resort Manoeuvres

• Zavanelli manoeuvre: replace the fetal head into the vagina (reverse restitution, then flex and push head back), followed by emergency caesarean section. Very rare. High morbidity.
• Symphysiotomy: surgical division of the pubic symphysis. Extremely rare in UK practice.
• Cleidotomy: deliberate fracture of the fetal clavicle (rarely performed on live infant)

Complications

Fetal

• Brachial plexus injury (Erb's palsy C5-C6 most common; Klumpke's C8-T1 rare)
  • Most (80-90%) resolve spontaneously within 12 months
  • Permanent injury in 2-16% of cases
• Humeral or clavicular fracture
• Hypoxic-ischaemic encephalopathy (if prolonged delay)
• Death (rare — 0.25-0.5% of shoulder dystocia cases)

Maternal

• PPH
• Third/fourth degree perineal tears
• Cervical/vaginal lacerations
• Psychological morbidity

Documentation and Debrief

• Detailed contemporaneous documentation is essential
• Record: time of delivery of head and body, manoeuvres used (in order), staff present, cord gases
• Debrief the woman and her partner within 24 hours
• Complete an incident report
• Offer physiotherapy referral if brachial plexus injury suspected in neonate

Important Facts for MRCOG

• McRoberts + suprapubic pressure should be the first manoeuvres attempted
• NEVER apply fundal pressure (worsens impaction, risk of uterine rupture)
• 50% of cases have no identifiable risk factors — anticipation alone is insufficient
• Previous shoulder dystocia: recurrence risk up to 25%
• Erb's palsy (C5-C6 upper trunk) is the most common brachial plexus injury
• Delivery of the posterior arm reduces bisacromial diameter effectively
• All manoeuvres should be documented in the order they were performed
• Time of head delivery and body delivery must be recorded

Source: RCOG Green-top Guideline No. 42 (2012 (reviewed 2017))

Read the original on rcog.org.uk

Clinically reviewed by NHS obstetricians and gynaecologists · Source last updated 2012 (reviewed 2017)

MRCOG AI is an independent educational tool. It is not affiliated with, endorsed by, or connected to the Royal College of Obstetricians and Gynaecologists (RCOG).