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Shoulder Dystocia

Extracted from Survival Guide to Midwifery, 2nd Edition (2012) Diane M. Fraser and Margaret A. Cooper, Oxford; Churchill Livingstone: 2012. Courtesy Elsevier

Shoulder dystocia is the failure of the shoulders to traverse the pelvis spontaneously after delivery of the head. Incidence is around 0.3 per cent of all deliveries. The anterior shoulder becomes trapped behind or on the symphysis pubis, while the posterior shoulder may be in the hollow of the sacrum or high above the sacral promontory. This is, therefore, a bony dystocia, and traction at this point will further impact the anterior shoulder, impeding attempts at delivery.

Risk factors

These can only give a high index of suspicion:

 

  • Post-term pregnancy
  • High parity
  • Maternal obesity (weight over 90 kg)
  • Fetal macrosomia (birth weight over 4000 g)
  • Maternal diabetes and gestational diabetes
  • Prolonged labour (first and second stages)
  • Operative delivery.

     

Warning signs and diagnosis

The birth may have been uncomplicated initially, but the head may have advanced slowly and the chin may have had difficulty in sweeping over the perineum. Once the head is born, it may look as if it is trying to return into the vagina. Shoulder dystocia is diagnosed when manoeuvres normally used by the midwife fail to accomplish birth.

Management

  • Summon help - an obstetrician, an anaesthetist and a person proficient in neonatal resuscitation
  • Attempt to disimpact the shoulders and accomplish delivery. An accurate and detailed record of the type of manoeuvre(s) used, the time taken, the amount of force used and the outcome of each attempted manoeuvre should be made
  • Try the procedures for 30-60 seconds; if the baby is not born, move on to the next procedure

Non-invasive procedures

 

Change in maternal position

  • McRoberts manœuvre. Help the woman to lie flat and to bring her knees up to her chest as far as possible to rotate the angle of the symphysis pubis superiorly and use the weight of her legs to create gentle pressure on her abdomen, releasing the impaction of the anterior shoulder
  • Suprapubic pressure. Pressure is exerted on the side of the fetal back and towards the fetal chest to adduct the shoulders and push the anterior shoulder away from the symphysis pubis. Can be used with the McRoberts manoeuvre.

Manipulative procedures

 

Delivery of the posterior arm: A. Location of the posterior arm; B. Directing the arm into the hollow of the sacrum; C. Grasping and splinting the wrist and forearm; D. Sweeping the arm over the chest and delivering the hand

Where non-invasive procedures have not been successful, direct manipulation of the fetus must now be attempted:

Positioning of the mother. McRoberts or the all-fours position may be used

Episiotomy. May be necessary to gain access to the fetus and reduce maternal trauma

Rubin's manoeuvre. The posterior shoulder is pushed in the direction of the fetal chest, thus rotating the anterior shoulder away from the symphysis pubis into the oblique diameter

Wood's manoeuvre. A hand is inserted into the vagina, pressure is exerted on the posterior fetal shoulder, and rotation is achievedReverse Wood's manoeuvre. Fingers on the back of the posterior shoulder apply pressure to rotate in opposite direction

Delivery of the posterior arm. A hand is inserted into the vagina, and two fingers splint the humerus of the posterior arm, flex the elbow and sweep the forearm over the chest to deliver the hand. If the rest of the delivery is not then accomplished, the second arm can be delivered following rotation of the shoulder using either Wood's or Rubin's manoeuvre or by reversing the Løvset manoeuvre. Has a high complication rate

Zavanelli manoeuvre. If the manoeuvres described above have been unsuccessful, the obstetrician may consider the Zavanelli manoeuvre. Requires the reversal of the mechanisms of delivery so far and success rates vary.

 

The 'HELPERR' mnemonic is widely used in obstetric drills:

  • Help
  • Episiotomy need assessed
  • Legs in McRoberts position
  • Pressure suprapubically
  • Enter vagina (internal rotation)
  • Remove posterior arm
  • Roll over and try again

Complications associated with shoulder dystocia

  • Postpartum haemorrhage.
  • Uterine rupture.
  • Neonatal asphyxia.
  • Erb's palsy.
  • Intrauterine death.

     

Further reading

Royal College off Obstetricians & Gynaecologists. (2012) Shoulder dystocia. Green-top guideline No 42. https://www.rcog.org.uk/globalassets/documents/guidelines/gtg42_25112013.pdf

Perinatal Institute. Perinatal Review - Obstetric emergencies: Shoulder dystocia. http://www.perinatal.nhs.uk/reviews/oe/oe_shoulder_dystocia.htm

Willacy H. (2013) Dystocia. (Professional reference) http://patient.info/doctor/dystocia

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