Shoulder dystocia is the impaction of fetal shoulders at the pelvic outlet after delivery of the head. Typically, the anterior shoulder is trapped behind the pubic symphysis, leading to delay of delivery of the rest of the infant. It usually occurs in the delivery of larger infants with disproportionately large shoulders compared with the fetal head. Although rare, shoulder dystocia is a serious concern because of the risk of fetal morbidity and mortality if it is not managed promptly and appropriately. Complications of shoulder dystocia include brachial plexus injury from overaggressive traction and fetal hypoxia from impaired respirations and compression of the umbilical cord, leading to compromised fetal circulation.
Shoulder dystocia is first recognized after the delivery of the fetal head, when routine downward traction is insufficient to deliver the anterior shoulder. After delivery of the infant's head, the head retracts tightly against the perineum (the "turtle sign"). 10 Upon recognizing shoulder dystocia, the physician should suction the infant's nose and mouth and call for assistance to position the mother in the extreme lithotomy position, with legs sharply flexed up to the abdomen (the McRoberts maneuver) with the legs held by the mother or an assistant. The bladder should be drained if this has not already been done. A generous episiotomy may also facilitate delivery. Next, an assistant should apply suprapubic pressure to disimpact the anterior shoulder from the pubic symphysis. It is important to remember never to apply fundal pressure, as this will further force the shoulder against the pelvic rim.11
To deliver the impacted anterior shoulder, a corkscrew maneuver (Wood's maneuver) is the first manipulation attempted. The physician grasps the posterior scapula of the infant with two fingers and rotates the shoulder girdle 180° in the pelvic outlet in an attempt to rotate the posterior shoulder into the anterior position and in the process deliver the shoulder. Gentle traction may then be applied as the patient pushes, and the infant is delivered through an oblique pelvic diameter. If the corkscrew maneuver fails to reduce the dystocia, the physician may then attempt to deliver the posterior shoulder. The physician's hand is passed posteriorly into the vagina until the infant's posterior arm is felt. The elbow is grasped and flexed, and the arm is delivered with the posterior shoulder. The anterior shoulder usually follows.
Was this article helpful?