When examining the topic of vaginal birth after cesarean (VBAC), uterine rupture is commonly cited as the major risk, but understanding exactly how it happens and who is most at risk for it to occur is a common source of confusion. Uterine rupture is an extremely serious complication, but it is also very rare. Although attempting a VBAC remains a safe option for women and offers many benefits, it is important to understand the potential risk of uterine rupture when considering attempting a trial of labor after cesarean section.

By basic definition, a uterine rupture is a tear in the wall of the uterus, most often at the site of a previous cesarean section incision. When a complete rupture occurs, the tear goes through all of the layers of the uterine wall, thus opening up the uterus to the abdominal cavity. The only treatment for a complete rupture is an emergency cesarean section. In some cases of complete uterine rupture, the baby is pushed through the uterine rupture site and is found floating in the mother’s abdominal cavity at the time of c-section. Many women who suffer a complete uterine rupture will also require a blood transfusion and some also require a hysterectomy.

Thankfully, uterine rupture is rare. According to a practice bulletin released by the American College of Obstetricians and Gynecologists in 2010, the rate of uterine rupture in women with a prior low transverse uterine incision is less than one percent and the incidence of fetal death in term pregnancies with a uterine rupture is less than three percent.

Predicting which women are most likely to have a uterine rupture can be difficult. As a general rule, women who have had a prior classical or T-incision on their uterus are more likely to rupture because the upper uterine segment where these incisions are made is not as strong and is more likely to be unable to tolerate the strength of contractions during labor. Thus, women who have these types of scars are likely to have a scheduled c-section before labor begins. Other risk factors for uterine rupture include an increased number of prior cesarean sections and giving birth less than 18 months after the most recent cesarean section.

While uterine rupture is rare, it is a risk that must be taken seriously. In a 2010 official consensus statement, the National Institute of Health recognized that a “trial of labor is a reasonable option for many pregnant women,” however ACOG adds that “a trial of labor after previous cesarean delivery should be undertaken at facilities capable of emergency deliveries.” Women should have continuous maternal and fetal monitoring during a trial of labor and should immediately report any symptoms of severe abdominal pain that does not go away between contractions and vaginal bleeding to her care provider. A uterine rupture can sometimes be difficult to definitively diagnose during labor, but it is typically accompanied by fetal heart rate decelerations and a loss of fetal station since the fetus often moves up into the abdominal cavity instead of down the birth canal during a complete rupture. Hospitals are the safest place to attempt a vaginal birth after cesarean in case a uterine rupture occurs and an emergency cesarean becomes necessary.

According to the NIH statement, “when trial of labor and elective repeat cesarean delivery are medically equivalent options, a shared decision making process should be adopted and, whenever possible, the woman’s preference should be honored.” While a VBAC is often the safest route of delivery, the risks of uterine rupture cannot be ignored. The decision to attempt a vaginal birth after cesarean should be made after carefully considering your personal risks and benefits with your care provider.

Sources:

1. Vaginal birth after previous cesarean delivery. Practice Bulletin No. 115. American College of Obstetricians and Gynecologists. Obstetrics & Gynecology. 2010; 116: 450–63.
2. Cunningham FG, Bangdiwala S, Brown SS, Dean TM, Frederiksen M, Rowland Hogue CJ, King T, Spencer Lukacz E, McCullough LB, Nicholson W, Petit N, Probstfield JL, Viguera AC, Wong CA, Zimmet SC. National Institutes of Health Consensus Development Conference Statement: Vaginal Birth After Cesarean: New Insights. March 8—10, 2010. Obstetrics & Gynecology. 2010; 115(6):1279–1295.