Definition of Shoulder Dystocia
Shoulder dystocia is defined as a vaginal birth where the obstetrician is unable to deliver the fetal shoulders with normal traction after delivery of the head, requiring additional maneuvers to complete the delivery. 1
Diagnostic Criteria
- Shoulder dystocia occurs when normal traction on the fetal head does not lead to delivery of the shoulders, creating an obstetric emergency 2
- It is characterized by impaction of the fetal shoulders in the maternal pelvis, specifically when the anterior shoulder becomes lodged behind the maternal pubic symphysis 2
- The diagnosis is made clinically when additional maneuvers beyond routine delivery techniques are required to deliver the shoulders 1
Risk Factors
- Fetal macrosomia (especially with estimated fetal weights >4,500g in diabetic mothers or >5,000g in non-diabetic mothers) 1
- Maternal diabetes (preexisting or gestational) 2
- Prior history of shoulder dystocia 2
- Prolonged second stage of labor 3
- Prolonged deceleration phase of labor (from 8-10 cm dilation) 3
- Arrest of descent during the second stage 3
Clinical Significance
- Shoulder dystocia is associated with significant risks of neonatal morbidity, including brachial plexus injuries and hypoxia 2
- Maternal complications include trauma to the bladder, anal sphincter damage, rectal injury, and postpartum hemorrhage 2
- A prolonged deceleration phase with disorders of fetal descent significantly increases the risk of shoulder dystocia if vaginal delivery occurs 3
Important Considerations
- Despite known risk factors, shoulder dystocia remains largely unpredictable, with most cases occurring without warning 4
- It is considered an unpreventable obstetric emergency that requires immediate recognition and appropriate management 5
- All obstetric providers should be prepared to manage this complication in every delivery, as the majority of cases occur in patients without identified risk factors 6
- Detailed documentation is essential following any delivery complicated by shoulder dystocia 6
Management Approach
- The McRoberts maneuver (hyperflexion of the mother's legs tightly to her abdomen) is recommended as the first-line intervention 1
- Suprapubic pressure may be applied simultaneously with the McRoberts maneuver to help dislodge the anterior shoulder 1
- If initial maneuvers fail, secondary techniques such as manual vaginal disimpaction may be necessary 1
- Simulation-based training for healthcare teams is strongly recommended to improve management skills and reduce morbidity 1
Shoulder dystocia remains one of the most challenging obstetric emergencies, requiring prompt recognition and systematic management to minimize complications for both mother and baby 7.