Shoulder dystocia

A vaginal cephalic delivery that requires additional obstetric manoeuvres to deliver the foetus after the head has delivered and gentle traction has failed.

• It results from either the anterior, or less frequently the posterior, impacting on the maternal pubic symphysis, or sacral promontory, respectively.

Background

•  Occurs in 0.5-0.8% of vaginal deliveris

Risk factors/Aetiology

• Poor contractions during labour / prolonged labour (e.g. secondary arrest)
  • Primigravida (1st child) may be more at risk because of this.
• Transverse/Breech baby
• Macrosomia
• Maternal Diabetes
• Maternal Obesity (BMI >30kg/m)
• Induced labour and oxytocin prescribing during labour
• Assisted vaginal delivery e.g. forceps or ventouse

Prevention measures

• Mothers with pre-existing or gestational diabetes should be offered induced delivery at 38 weeks (with or without macrosomia)
  • NB Induction should NOT be offered to non-diabetic mothers with macrosomia
• Previous shoulder dystocia does not necessarily indicate C-section in the future- decision should be made jointly with woman and the obstetric team

Recognising Shoulder Dystocia

• It is important to recognise the features of dystocia early and to get help early
• Some features may include
  • difficulty with delivering the face/chin
  • the head remaining tightly applied to the vulva or even retracting (turtle-neck sign)
  • failure of restitution of the head (rotating in line with the shoulders)
  • failure of the shoulder to descend
• ‘Normal’ traction (i.e. not more than would be used in a normal vaginal delivery) applied in the axial plane (in line with the spine) may be used to diagnose dystocia
  • Normally, the baby would progress with traction.  In shoulder dystocia, it won’t.

Management

• Stop the mother pushing
• McRoberts’ Manoeuvre
  •  the patient hyperflexes her hips so they are against her abdomen. Mothers in labour may not have enough energy to do this by themselves and may need the assistance of others in the room – which is usually the case. Posterolateral pressure is applied suprapubically with traction on the fetal head. This is the most effective procedure and should be performed first (success rates are up to 90%)
• If this does not work, episiotomy (cut between the vagina and anus) may be required and other manoeuvres attempted
  • e.g. Rubin’s and Woods’ screw, which involve pressing on the posterior shoulder and turning the anterior shoulder posteriorly, respectively
• Caesarean section should also be considered early on as a management if there is no response to McRoberts’ manoeuvre
• NB DO NOT APPLY FUNDAL PRESSURE as this may rupture the uterus.

Complications

• Brachial plexus palsies
  • Occurs in 2.3-16%.  90% of BPPs resolve without permanent disability.
• Postpartum haemorrhage (11%)
• Tearing
• Perinatal morbidity/mortality from hypoxia/acidosis

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