In 2002, 780,000 episiotomies were performed in the US. An episiotomy is an incision made during childbirth in a woman’s perineum, which lies between the vagina and the anus. An episiotomy is sometimes done during labor to enlarge the vaginal opening and reduce the risk of spontaneous vaginal tears during delivery. Episiotomies were once routinely performed during childbirth, due to the widely held belief that a cleanly made incision was better then the possibility of a jagged tear.

Situations that may merit an episiotomy include the vaginal delivery of a large baby or a breech birth, which is when the baby is coming out feet or bottom first. When the baby’s shoulders are too wide, one of them may get stuck against the mother’s pubic bone, a condition called shoulder dystocia . If the fetus’s lodged shoulder is forcibly pressed downward during delivery in order to free it, the nerves controlling movement and sensation in the arm (called the brachial plexus) can be injured. This condition is known as brachial plexus palsy (BPP). An infant’s chest can also become depressed from the same maneuver.

The use of an episiotomy in shoulder dystocia is somewhat controversial. Because it is done to soft tissue, an episiotomy alone will not release the shoulder from behind the mother’s pubic bone. It can, however, allow more room for the physician to maneuver the child in the birth canal, a technique called fetal manipulation . An episiotomy is not without risk: it may increase the chance of injury to the mother’s anal sphincter, which can lead to anal incontinence. A study published in the October 2004 issue of American Journal of Obstetrics and Gynecology compared births involving episiotomy, fetal manipulations, or both when shoulder dystocia occurred. The study found that episiotomies significantly increase risk of trauma to the mother, without reducing the risk of BPP for the child.

About the study

The study’s researchers reviewed several databases to find medical records of births complicated by shoulder dystocia. From the 592 identified cases, the researchers identified 127 of the most severe cases of shoulder dystocia and associated BPP. They divided these cases into three categories:

  • Fetal manipulation without episiotomy (57 cases)
  • Episiotomy without fetal manipulation (22 cases)
  • Episiotomy with fetal manipulation (48 cases)

Among the three groups, the researchers compared rates of BPP and chest depression in the infants, and anal sphincter trauma in the mothers.

The findings

The researchers found that in severe shoulder dystocia, fetal manipulation can be safely performed without episiotomy, reducing the increased risk of BPP in the infant while averting anal sphincter or perineum trauma in the mother.

In fact, when infants were maneuvered during delivery without episiotomy, BPP occurred significantly less. The rate of BPP was:

  • 35.1% in the fetal manipulation-only group
  • 59.1% in the episiotomy-only group
  • 58.3% in the episiotomy with fetal manipulation group

The rate of fetal chest depression was:

  • 14% in the fetal manipulation-only group
  • 9.1% in the episiotomy-only group
  • 18.8% in the episiotomy with fetal manipulation group

The rate of anal sphincter trauma was:

  • 10.7% in the fetal manipulation-only group
  • 68.2% in the episiotomy-only group
  • 62.5% in the episiotomy with fetal manipulation group

The researchers concluded that an episiotomy, with or without fetal manipulation, is associated with an almost seven-fold increase in the rate of severe perineal trauma without providing the benefit of reducing the occurrence of BPP or chest depression.

How does this affect you?

Shoulder dystocia can be a frightening emergency in the delivery room. While most cases occur without warning, risk factors have been identified. They include:

  • Gestational diabetes
  • Assisted vaginal delivery with forceps or vacuum
  • Prolonged labor
  • Suspected large size of fetus
  • Abnormal maternal pelvic anatomy
  • Maternal short stature

Although some situations warrant an episiotomy, this study strongly suggests that shoulder dystocia is not one of them. If you are pregnant—especially if your baby may be at increased risk for shoulder dystocia—talk with your doctor about the merits of having an episiotomy during your delivery. Don’t wait until you go into labor to have this conversation. Find out well in advance how he or she generally handles this potential problem, and make any concerns you have known.