The McRoberts maneuver is an obstetric procedure used as the first-line response to a complication that occurs after the baby’s head is delivered. Named after American obstetrician Dr. William A. McRoberts, Jr., the maneuver involves changing the mother’s positioning. The core action is hyperflexing the mother’s legs tightly toward her abdomen to alter the pelvic dimensions and free the baby’s shoulder.
Understanding Shoulder Dystocia
Shoulder dystocia is an emergency that occurs when the baby’s anterior shoulder becomes wedged behind the mother’s pubic bone after the head has successfully passed through the birth canal. This impaction prevents the rest of the baby’s body from being delivered, creating a sudden obstruction.
The condition is considered an obstetric emergency. Compression of the umbilical cord and the inability of the baby to breathe can lead to a lack of oxygen (asphyxia), potentially causing brain injury or death if not resolved quickly. Medical teams aim to resolve the impaction within a maximum of five minutes to prevent permanent neurological damage. The first visible sign of this complication is often the “turtle sign,” where the baby’s head emerges but then retracts slightly back against the perineum.
The Mechanics of the Maneuver
The McRoberts maneuver is performed by placing the mother flat on her back and removing any pillows from underneath her. An assistant on each side then sharply flexes the mother’s thighs toward her chest, bringing the knees up to her armpits. This extreme hip hyperflexion is a quick way to change the geometry of the maternal pelvis.
The physiological effect of this positioning increases the available space for the baby’s shoulder. The maneuver straightens the sacrum relative to the lumbar spine, flattening the lumbar lordosis. This action rotates the pubic symphysis (the joint connecting the pubic bones) superiorly, or toward the mother’s head. This rotation increases the functional anterior-posterior diameter of the pelvic outlet, allowing the trapped shoulder to pass. The maneuver is often performed simultaneously with suprapubic pressure, which involves applying gentle downward force above the pubic bone to help dislodge the impacted shoulder.
Success Rates and Potential Risks
The McRoberts maneuver is a low-risk first-line intervention, which is why it is widely recommended as the initial step. When performed alone, the maneuver successfully resolves shoulder dystocia in approximately 42% to 56% of cases. When combined with suprapubic pressure, its success rate increases, resolving up to 90% of cases.
The maneuver is considered one of the safest options, but it is not without potential risks for the mother. The extreme flexion of the hips can cause temporary discomfort and bruising. In rare instances, prolonged or forceful positioning can lead to nerve injury, such as femoral nerve neuropraxia, or separation of the pubic symphysis.
For the baby, the maneuver is intended to prevent injury by resolving the impaction swiftly. If the shoulder dystocia is severe or prolonged, or if excessive force is used, the baby remains at risk for birth injuries. The most common injuries are a clavicle fracture or a brachial plexus injury, which is damage to the network of nerves controlling movement and sensation in the arm and hand. The McRoberts maneuver is the initial step before a medical team attempts more complex, internal rotational procedures.