Reproductive · Obstetric Emergencies
The facts most likely to be tested
Shoulder dystocia is defined as the failure of the fetal shoulders to deliver spontaneously after the delivery of the fetal head.
The classic clinical presentation is the turtle sign, characterized by the retraction of the fetal head against the maternal perineum.
Macrosomia (estimated fetal weight >4500g in diabetic mothers or >5000g in non-diabetic mothers) is the most significant risk factor for shoulder dystocia.
The first-line maneuver for management is McRoberts maneuver, which involves maternal hip hyperflexion to flatten the sacrum and rotate the symphysis pubis.
Suprapubic pressure is applied to the fetal posterior shoulder to dislodge it from behind the maternal symphysis pubis.
Fundal pressure is strictly contraindicated because it can cause uterine rupture or further impaction of the fetal shoulder.
Brachial plexus injury (specifically Erb-Duchenne palsy) is the most common neonatal complication associated with shoulder dystocia.
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A 32-year-old G2P1 woman at 40 weeks gestation is undergoing a trial of labor. During the second stage of labor, the fetal head delivers, but the provider notes the head retracts against the perineum, a finding described as the turtle sign. Despite maternal pushing, the shoulders fail to deliver. The patient has a history of gestational diabetes and the estimated fetal weight is 4600g. The fetal heart rate tracing remains reassuring.
What is the most appropriate next step in management?
McRoberts maneuver
The patient presents with classic signs of shoulder dystocia, and the first-line intervention is the McRoberts maneuver to facilitate the release of the impacted anterior shoulder.
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Etiology / Epidemiology
Associated with macrosomia, maternal diabetes, and post-term pregnancy.
Clinical Manifestations
Failure of shoulders to deliver after head; turtle sign is pathognomonic.
Diagnosis
Clinical diagnosis; failure of routine traction to deliver shoulders.
Treatment
McRoberts maneuver is first-line; never apply fundal pressure.
Prognosis
Brachial plexus injury is the most common long-term complication.
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Epidemiology & Etiology
Occurs when the fetal anterior shoulder impacts against the maternal symphysis pubis. Primary risk factors include gestational diabetes, fetal macrosomia (>4500g), and a history of prior dystocia. It is an obstetric emergency requiring rapid, systematic intervention.
Pertinent Anatomy
The fetal shoulders are typically oriented in the oblique diameter of the pelvic inlet. Impaction occurs when the bisacromial diameter is larger than the anteroposterior diameter of the pelvic outlet.
Pathophysiology
Following delivery of the fetal head, the anterior shoulder fails to rotate into the oblique diameter. The shoulder becomes lodged behind the symphysis pubis, preventing further descent. Continued attempts at delivery without maneuvers risk brachial plexus injury or clavicular fracture.
Clinical Manifestations
The turtle sign—retraction of the fetal head against the perineum—is the pathognomonic clinical finding. The head delivers but then 'pulls back' into the introitus. Fundal pressure is strictly contraindicated as it further wedges the shoulder into the symphysis.
Diagnosis
Diagnosis is strictly clinical, defined by the inability to deliver the shoulders using routine downward traction. No imaging or laboratory tests are indicated. The diagnosis is made immediately upon the failure of the head to deliver the shoulders.
Treatment
Initiate the McRoberts maneuver (hyperflexion of maternal hips against the abdomen) as the first-line intervention. If unsuccessful, proceed to suprapubic pressure or rotational maneuvers (e.g., Woods corkscrew). Avoid excessive lateral traction to prevent permanent nerve damage.
Prognosis
The most significant risk is Erb’s palsy (C5-C6 injury). Other complications include clavicular fracture, humerus fracture, and fetal hypoxia. Most injuries resolve, but permanent neurological deficits occur in <10% of cases.
Differential Diagnosis
Occiput posterior position: head delivers face-up, not retracted
Nuchal cord: cord wrapped around neck, not shoulder impaction
Macrosomia: large fetus without shoulder impaction
Pelvic inlet contraction: cephalopelvic disproportion at the brim
Fetal anomaly: hydrocephalus or tumor preventing descent