What is the diagnosis for a 33-year-old woman, gravida 7 (number of times pregnant), para 6 (number of viable births), at 39 weeks gestation with hypertension (high blood pressure), who undergoes induction of labor and experiences shoulder dystocia (difficulty delivering the anterior fetal shoulder) after vaginal delivery of the fetal head?

From the Guidelines

This patient is experiencing a shoulder dystocia, a serious obstetric emergency requiring immediate intervention, and the management should follow a stepwise approach starting with the McRoberts maneuver, as recommended by the most recent and highest quality study available 1. The patient's condition is critical, and the management of shoulder dystocia should be prioritized to prevent morbidity and mortality. The McRoberts maneuver involves sharply flexing the mother's thighs against her abdomen to flatten the sacrum and rotate the symphysis pubis upward. This should be combined with suprapubic pressure applied by an assistant to push the anterior shoulder under the pubic symphysis.

• Risk factors in this case include maternal obesity (BMI 32), excessive weight gain, multiparity, possible macrosomia (suggested by large fundal height), and uterine fibroids which may distort the birth canal.
• If the McRoberts maneuver is unsuccessful, proceed to internal rotational maneuvers such as the Woods' screw maneuver (rotating the posterior shoulder) or Rubin maneuver (adducting the shoulders).
• Delivery of the posterior arm may be attempted if previous maneuvers fail.
• In severe cases, consider more aggressive approaches like the Zavanelli maneuver (cephalic replacement) or symphysiotomy, though these are rarely needed. The patient's hypertension, with a blood pressure of 160/96 mm Hg, should also be managed according to the most recent guidelines, which recommend labetalol or nifedipine as first-line treatment for hypertensive emergencies during pregnancy 1.
• The patient should be positioned appropriately, and an episiotomy may be considered to create more space.
• Documentation of the event, including timing of maneuvers and personnel present, is essential for medical-legal purposes. After delivery, evaluate both mother and infant for injuries such as brachial plexus injury, clavicular fracture, or maternal lacerations.

From the Research

Definition and Management of Shoulder Dystocia

• Shoulder dystocia is defined as a vaginal delivery that requires additional obstetric maneuvers to deliver the fetus after the head has delivered and gentle traction has failed 2.
• The management of shoulder dystocia involves the use of specific maneuvers, such as the McRoberts maneuver, suprapubic pressure, internal rotation, or removal of the posterior arm, to relieve the impacted shoulder and allow for spontaneous delivery of the infant 3.

Risk Factors for Shoulder Dystocia

• The main risk factors for shoulder dystocia are previous shoulder dystocia and macrosomia, but they are poorly predictive, and 50-70% of shoulder dystocia cases occur in their absence 2.
• Other risk factors include gestational diabetes, obesity, and a history of previous shoulder dystocia 2, 4.

Maneuvers for Relieving Shoulder Dystocia

• The McRoberts maneuver, with or without suprapubic pressure, is recommended as the first-line treatment for shoulder dystocia 2, 5.
• If the McRoberts maneuver is unsuccessful, other maneuvers such as Wood's maneuver or delivery of the posterior arm may be performed 2, 6.
• The "HELPERR" mnemonic is a useful tool for addressing shoulder dystocia, and it aids physicians in completing one of three actions: enlarging the maternal pelvis, collapsing the fetal shoulder width, or altering the orientation of the longitudinal axis of the fetus to the plane of the obstruction 3.

Predictive Factors for the Success of McRoberts' Maneuver

• The success rate of the McRoberts maneuver is higher after spontaneous vaginal delivery (47.7%) compared to instrumental delivery (15.0%) 5.
• Instrumental delivery is a significant factor associated with an increased risk of failed McRoberts maneuver 5.

Recommendations for Prevention and Management

• Induction of labor is recommended in case of impending macrosomia if the cervix is favorable and gestational age is greater than 39 weeks of gestation 2.
• Cesarean delivery is recommended before labor in case of estimated fetal weight greater than 4500g if associated with maternal diabetes, or greater than 5000g in the absence of maternal diabetes 2.
• Physical activity is recommended before and during pregnancy to reduce the occurrence of some risk factors for shoulder dystocia 2.