Because shoulder dystocia cannot be accurately predicted, clinicians should be well versed in its management principles. Because of ongoing cord compression with this dystocia, one goal is to reduce the head-to-body delivery time. This is balanced against the second goal, which is avoiding fetal and maternal injury from aggressive manipulations. Accordingly, an initial gentle attempt at traction, assisted by maternal expulsive eforts, is recommended. Adequate analgesia is certainly ideal. Some clinicians advocate performing a large episiotomy to provide room for manipulations. Episiotomy itself does not lower brachial plexus injury rates but raises third-and fourthdegree laceration rates (Gurewitsch, 2004; Paris, 2011; SagiDain, 2015). Episiotomy may be elected to complete needed maneuvers.
After gentle traction, various techniques can be used to free the anterior shoulder from its impacted position behind the symphysis pubis. A more detailed discussion of these and the topic is found in Cunningham and Gilstrap s Operative Obstetrics, 3rd edition (Cunningham, 2017). Of these, moderate suprapubic pressure can be applied by an assistant, while downward trac tion is applied to the fetal head. Pressure is applied with the heel of the hand to the anterior shoulder wedged above and behind the symphysis. The anterior shoulder is thus either depressed or rotated, or both, so the shoulders occupy the oblique plane of the pelvis. Here, the anterior shoulder can be freed.
The McRoberts maneuver is often selected next if additional steps are needed. The maneuver consists of removing the legs from the stirrups and sharply lexing them up toward the abdomen. Suprapubic pressure is often concurrently applied (Fig. 27-5). Gherman and associates (2000) analyzed the McRoberts maneuver using x-ray pelvimetry. hey found that the procedure caused straightening of the sacrum relative to the lumbar vertebrae, rotation of the symphysis pubis toward the maternal head, and a decrease in the angle of pelvic inclination. Although this does not increase pelvic dimensions, pelvic rotation cephalad tends to free the impacted anterior shoulder. Gonik and coworkers (1989) tested the McRoberts position objectively with laboratory models and found that the maneuver reduced the forces needed to free the fetal shoul der. If unsuccessful, most move next either to free the posterior shoulder or to rotate the bisacromial diameter into one of the oblique diameters of the maternal pelvis.
With delivey of the posterior shoulder, the accoucheur carefully sweeps the posterior arm of the fetus across its chest, followed by deliveY of the arm (Fig. 27-6). If possible, the operator's ingers are aligned parallel to the long axis of the fetal humerus to lower bone fracture risks. The shoulder girdle is then rotated into one of the oblique diameters of the pelvis with subsequent delivery of the anterior shoulder.
Of rotational maneuvers, Woods (1943) reported that by progressively rotating the posterior shoulder 180 degrees in a corkscrew fashion, the impacted anterior shoulder could be released. his is frequently referred to as the Woods corkscrew maneuver (Fig. 27-7). Rubin (1964) recommended two maneuvers. First, the fetal shoulders are rocked from side to side by applying force to the maternal abdomen. If this is not successful, the pelvic hand reaches the most easily accessible fetal shoulder, which is then pushed toward the anterior surface of the chest. This maneuver most oten abducts both shoulders, which in turn produces a smaller bisacromial diameter. This permits displacement of the anterior shoulder from behind the symphysis (Fig. 27-8).