A new study to be published in the April issue of Obstetrics and Gynecology demonstrates that in the wake of a uterine rupture, providers have no more than 18 minutes to deliver the baby before the baby experiences significant hypoxia, and only 30 minutes until the baby suffers major neurological impairment.
The paper, entitled Uterine Rupture With Attempted Vaginal Birth After Cesarean Delivery: Decision-to-Delivery Time and Neonatal Outcome by Calla Holmgren et al. was undertaken to provide the most accurate information possible about the conditions needed to make attempted vaginal birth after cesarean (VBAC) as safe as possible.
The authors note:
The increasing rate of primary and repeat cesarean delivery in the United States is of concern to physicians and patients, and vaginal birth after cesarean delivery is considered to be one way to lower the overall cesarean delivery rate. Trial of labor after cesarean delivery (TOLAC), which peaked at 31% in 1998, has decreased progressively since (8.5% by 2006), primarily because of issues surrounding uterine rupture. Although rupture of the uterus during TOLAC is rare, it can be devastating for both the mother and neonate when it occurs, and it is a major liability risk for physicians. The American College of Obstetricians and Gynecologists’ guidelines advise physicians that TOLAC is most safely undertaken in hospitals where staff can immediately carry out an emergency cesarean delivery. This view is based on the premise that the ability to rapidly intervene will minimize adverse neonatal outcomes. However, immediate availability is loosely defined, and it is not clear how rapidly the fetus must be delivered after uterine rupture to prevent neonatal death or neurologic sequelae. The purpose of this study was to examine whether an association exists between neonatal outcomes and the time from diagnosis of uterine rupture to delivery of the neonate.In other words, should hospitals refuse a trial of labor to women with a previous C-section if they cannot guarantee that both an obstetrician and and anesthesiologist are on site to start a C-section with less than a half hour?
What did they look for?
The primary adverse outcome was defined as an abnormal umbilical pH level less than 7.0 or a 5-minute Apgar score of 7 or less. Secondary adverse outcomes included fetal or early neonatal death and neonatal neurologic injury attributed to uterine rupture. Neonatal neurologic injury was defined as otherwise unexplained seizures, clinically obvious cerebral palsy, or developmental delay attributable to hypoxia resulting from the uterine rupture.Who was included in the study?
Within the 10 hospitals studied, 40,772 women were identified with a prior cesarean delivery between January 1, 2000, through December 31, 2009. Of these, 11,195 women (27.5%) attempted TOLAC, with successful vaginal delivery for 9,419 (84.1%) patients... In total, there were 36 cases of documented uterine rupture (0.32%) during TOLAC.What did they find?
Of the 36 patients, 13 (36.1%) met our criteria for a primary adverse outcome of umbilical artery pH level less than 7.0 or 5-minute Apgar score less than 7. These patients were compared with the 23 patients without this outcome. Median (range) time to delivery for the primary adverse outcome group (n=13) was 19 (9–40) minutes compared with 14 (0 –38) for the nonadverse outcome group. Results after stratifying the sample by hospital type yield a similar result, with those experiencing the primary outcome having, on average, a 5.5-minute (95% confidence interval [CI] 0.0 –15.0) longer time to delivery than those who did not experience the outcome...
Seventeen neonates (47.2%) were delivered less than 18 minutes after identification of uterine rupture. Of these, two neonates had an abnormal 5-minute Apgar score, but both of these neonates had an umbilical pH level greater than 7.0 and none had neurologic injury. Eighteen patients were delivered more than 18 minutes after suspicion of uterine rupture (50.0%). Of these, 11 met criteria for a primary adverse outcome and three met criteria for an adverse secondary outcome. One patient did not have suspected uterine rupture during labor.
Seventeen neonates (47.2%) were delivered less than 18 minutes after identification of uterine rupture. Of these, two neonates had an abnormal 5-minute Apgar score, but both of these neonates had an umbilical pH level greater than 7.0 and none had neurologic injury. Eighteen patients were delivered more than 18 minutes after suspicion of uterine rupture (50.0%). Of these, 11 met criteria for a primary adverse outcome and three met criteria for an adverse secondary outcome. One patient did not have suspected uterine rupture during labor.A chart of the data makes the relationship between time to delivery and risk of adverse outcomes quite clear.
More than 83% of babies delivered more than 30 minutes after uterine rupture experienced major neurological complications.
As the authors explain:
Our study focused on serious neurologic morbidity in cases of confirmed uterine rupture during TOLAC. In 36 cases of acute uterine rupture, there were no fetal or neonatal deaths. Delivery within less than 18 minutes was associated with adverse primary outcome in two cases, but this was based on a 5-minute Apgar score less than 7; both neonates had normal umbilical pH levels. Three neonates in our study sustained long-term neurologic damage. These neonates were delivered 31, 40, and 42 minutes after uterine rupture was suspected on clinical grounds. When uterine rupture was identified in a timely fashion and delivery occurred in less than 30 minutes, there was no long-term neonatal morbidity in our study. However, delivery within 30 minutes did not prevent every case of low umbilical cord pH level or low 5-minute Apgar score, so these results should be interpreted with caution...The authors conclude:
Uterine rupture during TOLAC is a rare but serious complication that requires prompt recognition and delivery of the fetus. The response time necessary to prevent neonatal injury has been uncertain and controversial. In our study, all neonates delivered within 18 minutes from decision to delivery had normal umbilical cord pH levels. Delivery within 30 minutes was associated with good long-term outcomes...This is an important study that has the potential for wide impact. The study strongly confirms the ACOG recommendation that babies should be delivered as soon as possible in the wake of a uterine rupture. Intervals longer than 18 minutes resulted in demonstrable hypoxia and intervals longer than 30 minutes resulted in major neurological impairment. Studies like these make it extremely unlikely that hospitals and malpractice insurers will liberalize access to VBAC.
This piece first appeared on The Skeptical OB in March 2012.