What is a Shoulder Dystocia?
A shoulder dystocia is a complication encountered at the time of vaginal delivery. This occurs when a baby’s head has delivered, but the shoulders are stuck in the birth canal and do not deliver using standard delivery technique. Complicating approximately 1.5 percent of all vaginal deliveries, this obstetric emergency is often unpredictable, but it is something that obstetricians and midwives must recognize and treat quickly.
After the delivery of a baby’s head, the shoulders should deliver easily with gentle downward guidance by the obstetric provider. If they remain stuck, however, a shoulder dystocia is recognized and additional delivery techniques will be used to deliver the baby. These often include flexing the mother’s legs further back to make more room, using pressure above the pubic bone to try to dislodge the stuck shoulder, rotating the baby in the birth canal to help the shoulder slip out, cutting an episiotomy, fracturing the baby’s clavicle to make the diameter between the shoulders smaller, and occasionally having the mother turn on a hands-and-knees position to make more room in the pelvis. Thankfully, the majority of shoulder dystocias quickly resolve with one or two maneuvers (and usually the less dramatic ones!).
While the majority of shoulder dystocia cases are in women who have no risk factors, certain risk factors do make shoulder dystocia more likely. These include diabetes in pregnancy, a history of a prior dystocia, fetal macrosomia, and maternal obesity, to name a few.
Mothers whose births are complicated by a shoulder dystocia are more likely to have more severe vaginal lacerations as well as increased blood loss at the time of delivery. Indeed, the stress of such a dramatic birth can also be difficult to recover from, especially if her baby has any ongoing issues as a result of the delivery.
Most babies born after a shoulder dystocia do fine without any complications. Clavicular (or collar bone) fracture—which may be done intentionally to assist with delivery or indirectly at the time of birth—often heals without consequence. Additionally, a bundle of nerves that lie in the upper arm called the brachial plexus may be stretched and injured at the time of a shoulder dystocia. This can lead to a condition called brachial plexus palsy, in which a newborn will have a weakened or paralyzed hand or arm that does not grasp or spontaneously lift up.
Thankfully, brachial plexus palsies occur in only about 1 to 17 percent of all deliveries complicated by shoulder dystocia, and the majority are temporary and resolve with time. In fact, of babies who have brachial plexus palsy diagnosed at the time of birth, only 0.5-1.5 percent of them will still show signs of it at 1 year old. While most cases resolve spontaneously, some babies may benefit from physical therapy and (rarely) surgical treatment.
The most severe cases of shoulder dystocia can result in brain injury and death. This is because the baby’s brain is deprived of oxygen when the umbilical cord is compressed. Thankfully, this catastrophic outcome is usually only seen in the worst cases of shoulder dystocia that last extremely long—which is the exception, not the rule.
While knowing about shoulder dystocia can be worrisome, you should rest assured that this is a complication that all doctors and midwives have trained for in great detail. Many hospitals do routine simulations or drills so that everyone is prepared for when the real thing happens.
Sources:
- The American Congress of Obstetricians and Gynecologists
- Practice Bulletin #40: Shoulder dystocia.
The American Congress of Obstetricians and Gynecologists Task Force of Neonatal Brachial Plexus palsy - Neonatal brachial plexus palsy.
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