Commentary
Lessons learned from the history of VBAC
As VBACs became more common, the approach to the procedure became more relaxed. VBACs went from only being performed in tertiary care hospitals...
The relative safety of vaginal birth after cesarean (VBAC) has been documented in several large-scale studies in the past 15 years, and was affirmed in 2010 through a National Institutes of Health consensus development conference and a practice bulletin from the American College of Obstetricians and Gynecologists. Yet, despite all this research and review, rates of a trial of labor after cesarean (TOLAC) have increased only modestly in the last several years.
Approximately 20% of all births in 2013 in women with a history of one cesarean section involved a trial of labor, according to a recent report from the Centers for Disease Control and Prevention. This represents only a small increase from 2006, when the TOLAC rate had plummeted to approximately 15%.
The limited change is concerning because up to two-thirds of women with a prior cesarean delivery are candidates for a trial of labor, and many of them are excellent candidates. In total, 70% of the women who attempted labor in 2013 after a previous cesarean had successful VBACs, the CDC data shows.
Dr. Mark B. Landon
Several European countries have TOLAC rates between 50% and 70%, but in the United States, as evidenced by the recent CDC data, there continues to be an underutilization of attempted VBAC. We must ask ourselves, are women truly able to choose TOLAC, or are they being dissuaded by the health care system?
I believe that the barriers are still pervasive. Too often, women who are TOLAC candidates are not receiving appropriate counseling – and too often, women are not even being presented the option of a trial of labor, even when staff are immediately available to provide emergency care if needed.
Rupture concerns in perspective
When the NIH consensus development panel reviewed VBAC in 2010, it concluded that TOLAC is a reasonable option for many women with a prior cesarean. The panel found that restricted access to VBAC/TOLAC stemmed from existing practice guidelines and the medical liability climate, and it called upon providers and others to “mitigate or even eliminate” the barriers that women face in finding clinicians and facilities able and willing to offer TOLAC.
ACOG’s 2010 practice bulletin also acknowledged the problem of limited access. ACOG recommended, as it had in an earlier bulletin, that TOLAC-VBAC be undertaken in facilities where staff are immediately available for emergency care. It added, however, that when such resources are not available, the best alternative may be to refer patients to a facility with available resources. Health care providers and insurance carriers “should do all they can to facilitate transfer of care or comanagement in support of a desired TOLAC,” ACOG’s document states.
Why, given such recommendations, are we still falling so short of where we should be?
A number of nonclinical factors are involved, but clearly, as both the NIH and ACOG have stated, the fear of litigation in cases of uterine rupture is a contributing factor. A ruptured uterus is indeed the principal risk associated with TOLAC, and it can have serious sequelae including perinatal death, hypoxic ischemic encephalopathy (HIE), and hysterectomy.
We must appreciate, however, that the absolute rates of uterine rupture and of serious adverse outcomes are quite low. The rupture rate in 2013 among women who underwent TOLAC but ultimately had a repeat cesarean section – the highest-risk group – was 495 per 100,000 live births, according to the CDC. This rate of approximately 0.5% is consistent with the level of risk reported in the literature for several decades.
In one of the two large observational studies done in the United States that have shed light on TOLAC outcomes, the rate of uterine rupture among women who underwent TOLAC was 0.7% for women with a prior low transverse incision, 2.0% for those with a prior low vertical incision, and 0.5% for those with an unknown type of prior incision. Overall, the rate of uterine rupture in this study’s cohort of 17,898 women who underwent TOLAC was 0.7% (N Engl J Med. 2004 Dec 16;351[25]:2581-9). The study was conducted at 19 medical centers belonging to the Eunice Kennedy Shriver National Institute of Child Health and Human Development’s Maternal-Fetal Medical Units (MFMU) Network.
The second large study conducted in the United States – a multicenter observational study in which records of approximately 25,000 women with a prior low-transverse cesarean section were reviewed – also showed rates of uterine rupture less than 1% (Am J Obstet Gynecol. 2005 Nov;193[5]:1656-62).
The attributable risk for perinatal death or HIE at term appears to be 1 per 2,000 TOLAC, according to the MFMU Network study.