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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.
These can only give a high index of suspicion:
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.
Change in maternal position
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:
Complications associated with shoulder dystocia
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