PassFinals
Obstetrics

Shoulder Dystocia

Shoulder dystocia is impaction of a fetal shoulder against the maternal pelvis after the head has delivered, so the shoulders will not follow routine axial traction.

In a nutshell

Shoulder dystocia is failure of the shoulders to deliver after the head despite routine axial traction. Declare it aloud, call help, stop the pushing, lie her flat and perform McRoberts with suprapubic pressure, then move through the sequence without pausing.

Classic presentation

The head delivers and retracts against the perineum, restitution (the head turning to line up with the shoulders) fails, and the shoulders do not follow.

Key points

  • Incidence is 0.58% to 0.70% of vaginal births in the largest series.
  • Conventional risk factors predicted only 16% of the shoulder dystocias that caused infant morbidity, so risk assessment cannot prevent most cases.
  • Birth weight is a poor gate: 48% of cases are babies under 4000 g, and most babies of 4500 g or more deliver without difficulty.
  • At identical birth weight, babies of diabetic mothers have a two- to four-fold higher risk. Ultrasound is not recommended for prediction without another risk factor.
  • Brachial plexus injury complicates 2.3% to 16% of shoulder dystocias, and fewer than 10% leave permanent neurological dysfunction.
  • The UK and Ireland incidence of brachial plexus injury was 0.43 per 1000 live births.
  • 47% of the deaths in the Confidential Enquiry into Stillbirths and Deaths in Infancy occurred within five minutes of the head being delivered.

First-line investigation

None: the diagnosis is clinical. The shoulders fail to deliver with routine axial traction, so note the time the head delivered and start the sequence.

Management

First seconds: declare, call, stop pushing

  • Name it aloud: 'this is shoulder dystocia'. Write down the time of head delivery. Over 60 seconds head to body is the proposed objective diagnosis.1,2
  • Who to summon: extra midwifery help with the labour ward coordinator, an experienced obstetrician, an anaesthetist and the neonatal resuscitation team.2
  • Discourage maternal pushing: it worsens the impaction. Never apply fundal pressure, which carries a high neonatal complication rate and may rupture the uterus.2

McRoberts, then suprapubic pressure

  • Lay her flat, remove the pillows from under her back and take her legs out of lithotomy supports. One assistant each side: hyperflex and abduct the hips.2
  • Thighs onto the abdomen: reported success as high as 90%. Then test with routine axial traction once, normal-delivery force, along the fetal spine, no lateral pull.2
  • Still impacted: an assistant presses just above the symphysis pubis, from the side of the fetal back, downward and lateral. Continuous or rocking, no clear difference.2
  • Test again the same way. Never pull downward or laterally on the head. If the anterior shoulder is still not free, go internal.2

Internal manoeuvres or all fours

  • Episiotomy is not routine and does not relieve a bony obstruction. Cut only if your whole hand cannot easily enter the vagina.2
  • Go in posteriorly with the whole hand; the sacral hollow gives the most room. Move her to the bed end first.2
  • Push on the back of the posterior shoulder: this adducts it and turns the pair into the oblique, up to 180 degrees (Woods, Rubin).2
  • Or grasp the fetal wrist and draw the posterior arm out in a straight line. Humeral fracture follows in 2% to 12%, probably reflecting case severity.2
  • All fours succeeded in 83% in one case series. Prefer it for a slim, mobile woman without an epidural and a single attendant.2

Third line, rarely needed

  • The guideline sets no time limit, but injury was rare while head to body stayed under five minutes. Keep moving; do not re-try a failed manoeuvre.2
  • Experienced operator only: cleidotomy (divide or bend the clavicle), symphysiotomy (high serious maternal morbidity) or Zavanelli (replace the head, then caesarean birth).2

After the birth

  • A neonatal clinician examines the baby: brachial plexus injury, humeral or clavicular fracture, pneumothorax, hypoxic brain damage. Erb palsy gives the waiter's tip posture.2,3
  • Maternal cost: 11% postpartum haemorrhage, 3.8% third- or fourth-degree tear. The number and type of manoeuvres used do not change either rate.2
  • Primary postpartum haemorrhage is 500 mL or more within 24 hours; major is above 1000 mL. Treat it on the postpartum haemorrhage pathway.4

Document, explain, train

  • Record the time of head and body delivery, staff present, each manoeuvre in order, the traction used and the maternal position. Explain the birth to the parents.2
  • Shoulder dystocia training is required at least annually for every member of maternity staff, and annual skill drills sit in the Clinical Negligence Scheme for Trusts (CNST) maternity standards.2
  • Recurrence is about one in ten, so discuss vaginal birth against planned caesarean for the next pregnancy before she leaves maternity care.3

Exam traps

  • Suprapubic pressure, not fundal pressure. Fundal pressure is the classic wrong answer and is prohibited outright by the guideline.
  • Putting her in McRoberts before the head delivers prevents nothing. Prophylactic positioning is explicitly not recommended.
  • Cutting an episiotomy will not free a bony impaction and does not lower brachial plexus injury risk. It buys hand room, nothing else.
  • Downward or lateral traction on the head is the traction linked to plexus avulsion, in cadaver work and in a Swedish series. Pull axially only.
  • A normal estimated fetal weight does not exclude shoulder dystocia, and most babies of 4500 g or more never have it.
  • Not every brachial plexus injury follows traction: in one series 4% occurred after caesarean birth.
  • In most fatal cases reviewed, the fetal heart rate trace was already abnormal before the dystocia, so it is often the last insult, not the only one.

Illustrations

McRoberts manoeuvre and suprapubic pressureAn illustration of McRoberts position with maternal hip hyperflexion and an assistant applying suprapubic pressure to the anterior shoulder.geraldbaeck, Wikimedia Commons · CC0
Erb palsy postureA clinical photograph of an infant with the affected arm adducted and internally rotated at the shoulder, extended at the elbow and pronated in the classic waiter's-tip posture of Erb palsy.r, Wikimedia Commons · CC-BY-SA-4.0

Key sources

  1. Royal College of Obstetricians and Gynaecologists (RCOG), Green-top Guideline No. 42: Shoulder Dystocia (Second edition, March 2012. The RCOG guideline page states that this is the second edition and that the third edition is currently in development, and that the page was last reviewed 28 March 2012. The page summary carries the definition, the proposed head-to-body threshold of more than 60 seconds, postpartum haemorrhage 11%, third- and fourth-degree tears 3.8% and brachial plexus injury 2.3% to 16%. The content-management publish date of March 2022 shown in the page metadata is a website artefact, not an edition.)Updated 28 Mar 2012
  2. RCOG Green-top Guideline No. 42: Shoulder Dystocia, full guideline (PDF, 18 pages) (Second edition, March 2012. Sections used here: 1 (incidence, maternal and neonatal complication rates), 4.1 (prediction), 6.3.1 to 6.3.3 (the ordered manoeuvre sequence), 6.4 (care of mother and baby after the birth) and 7.1.1 (training). The definitions of routine and axial traction, and the statement that prophylactic McRoberts positioning before the head delivers is not recommended, sit on page 6 immediately before section 6.3.1. Appendix 2, the RCOG algorithm, is a scanned image and carries no extractable text; sections 6.3.1 to 6.3.3 give the same sequence in prose.)
  3. RCOG patient information: Shoulder dystocia (Published March 2013 and based on Green-top Guideline No. 42. Used here for the risk-factor list, the advice against ultrasound for prediction, the position on induction and caesarean birth, the recovery pattern of Erb palsy and the approximately one in ten recurrence risk in a later pregnancy.)
  4. RCOG Green-top Guideline No. 52: Prevention and Management of Postpartum Haemorrhage (Second edition; the RCOG page states that the third edition is currently in development and that the page was last reviewed 16 December 2016. Used here only for the postpartum haemorrhage blood-loss definitions: primary postpartum haemorrhage is 500 mL or more from the genital tract within 24 hours, minor is 500 to 1000 mL and major is more than 1000 mL. Drug treatment of postpartum haemorrhage is not restated in this chapter; see the postpartum haemorrhage chapter.)Updated 16 Dec 2016

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.