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Last Update: 03/27/2025 09:41 PM

Current Deck: ACG Part 2::Obstetrics

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SS_OB 1.34 Discuss the anaesthetic management of problems that may arise with labour and delivery, including the following situations:
- Shoulder dystocia 
Shoulder Dystocia
  • 1/750 obstetric emergency.
  • Difficulty in delivering the shoulders when they become impacted on the maternal bony pelvis after delivery of the head.
  • Planned LSCS may be offered for suspected fetal macrosomia with estimated fetal weights >5000g in women without diabetes and 4500g in those with diabetes.
Risk factors
  • Maternal: abnormal pelvic anatomy, GDM, post-term pregnancy, PHx of dystocia, short stature, obesity, excessive weight gain.
  • Labor-related: instrumental vaginal delivery, prolonged 1st and 2nd stages of labor.
  • Fetal: fetal macrosomia, post-date pregnancy, fetal anomalies.
Pathophysiology
  • Fetal head and shoulders rotate to make use of the widest diameters in the pelvis.
  • The anterior shoulder impacts on maternal pubis symphysis, and the posterior shoulder on the sacral promontory.
  • Traction and maternal expulsive efforts are unable to deliver the fetus.
  • After delivery of the head, the umbilical cord is compressed between the fetal body and maternal pelvis, limiting oxygen supply to the fetus.
    • Only a few minutes to deliver without significant risk of asphyxia and death (fetal pH falls by 0.04/minute).
    • Vessels in the fetal neck are occluded, and cerebral damage will occur if delivery is delayed significantly.
  • Mother: soft tissue injuries (perineum, rectum, bladder, urethra), PPH.
  • Fetus: fracture of humerus or clavicle, damage to brachial plexus (recovery usually complete within 12 months), Erb’s palsy (C5-6), or Klumpke’s palsy (C8-T1).
Diagnosis
  • Baby’s head does not emerge with standard moderate traction and maternal pushing after delivery of the head.
  • “Turtle” sign: fetal head retracts back against the perineum, baby's cheeks bulge out.
Obstetric management
  • Recognition of women with risk factors.
  • Call for help: additional midwives, theatre for LSCS, anaesthetics, paediatrics (for newborn resus).
  • Place woman in dorsal lithotomy position, perform episiotomy, and apply gentle downward traction to the fetal head.
  • If delivery is not achieved, attempt the following maneuvers (spend no more than 30-60 seconds on each):
    • McRobert’s maneuver: flex hips and position thighs on abdomen + suprapubic pressure to dislodge the anterior shoulder + gentle downward traction.
    • Wood’s Screw maneuver: reach to locate the posterior shoulder and attempt to rotate it anteriorly to dislodge the shoulder.
    • Attempt delivery of posterior shoulder (sweep arm across fetal chest) + gentle traction.
    • Rotate woman onto all fours to maximize pelvic outlet diameter.
  • Other measures:
    • Deliberately fracture anterior clavicle by pressing it against the pubis symphysis.
    • Symphisiotomy or CS (with tocolytics).
  • Avoid: fundal pressure, left lateral position, inappropriate traction on the head.
  • Careful recording to include time of delivery of head and body, maneuvers used, and personnel involved.
Anaesthetic management
  • May be required for:
    • Emergency LSCS if baby cannot be delivered vaginally.
    • Uterotonic agents to assist cephalic replacement.
    • Management of PPH and 3rd & 4th degree tears.
References

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