Snapshot A 26-year-old G1P0 woman with a history of diabetes mellitus is undergoing a vaginal delivery at 42 weeks of gestation. After emergence then retraction of the baby's head, the obstetrician finds that the baby's shoulders are not delivering with ease. Various maneuvers are performed to reposition the baby before successful delivery. The newborn baby's birth weight is 4300 grams. The baby is noted postpartum to have difficulty moving the left arm, which is internally rotated and limp. (Erb-Duchenne palsy) Introduction Overview shoulder dystocia is an obstetric complication of cephalic vaginal delivery that occurs when the anterior shoulder of the fetus is impacted behind the pubic symphis during vaginal delivery Associated risk factors history of shoulder dystocia in a prior vaginal delivery fetal macrosomia maternal gestational diabetes insulin is a growth factor resulting in macrosomia maternal obesity excessive weight gain (> 35 lbs.) during pregnancy post-term pregnancy Epidemiology Incidence 0.5-3% of vaginal deliveries Demographics fetuses undergoing cephalic vaginal delivery after 34 weeks of gestation ETIOLOGY Pathophysiology mechanical obstruction to proper fetal shoulder rotation to the mother's pelvic diameter fetal shoulder dimensions may be too large maternal pelvis may be too narrow Presentation Physical exam "turtle sign" retraction of the fetal head, after emergence, back into the vaginal introitus double chin sign in the fetus Treatment Medical fetal and maternal maneuvers goal is to reposition the laboring mother and/or the fetus to reduce impaction of the fetus's shoulders flexion of maternal hips (McRoberts maneuver) rotation of fetal shoulders 180 degrees (Wood's corkscrew) suprapubic pressure applied downward pressure to the maternal abodmen just above the pubic symphysis Surgical emergent cesarean section after pushing the fetal head back into the mother's vaginal introitus Complications Fetal brachial plexis damage most common complication of shoulder dystocia secondary to severe traction of the neck away from the anterior shoulder classically presents as Erb-Duchenne palsy more rarely presents with Klumpke palsy that features hyperextension of the wrist extension of the metacarpophalangeal joints flexion of the proximal and distal interphalangeal joints Clavicle fracture or misalignment in the fetus Fetal hypoxia secondary to stalled delivery with the fetal head outside the vagina and the fetal body inside the vagina Prognosis Patients with upper brachial plexus lesions (i.e., Erb-Duchenne palsy) have a better prognosis than those with lower brachial plexus lesions (i.e., Klumpke palsy) 90-95% of upper brachial plexus injuries resolve 60% of lower brachial plexus injuries resolve