Vaginal Birth After Previous Cesarean Delivery (VBAC)
VBAC has become a focus of controversy again after a study last summer in TheNew England Journal of Medicine. For the past 20 years, the practice of VBAC has been encouraged to lower the cesarean section rate, which was 22.9% in the United States in the year 2000. This recent article describes a population-based study conducted in Washington State from 1987-1996. Dr. Lyndon-Rochelle found a similar incidence of uterine rupture as that found in previous studies (5.2 uterine ruptures per 1000 women for spontaneous labor, or 0.5%). In women who were induced with pitocin without prostaglandins, the rate of rupture was 7.7 per 1000 women. However, the rates of uterine rupture were 24.5 per 1000 in women with prostaglandin-induced labor. Although there have been warnings not to use misoprostol (prostaglandin E1) in patients attempting VBAC, many obstetricians have continued to use prostaglandin E2 (Cervidil, dinoprostone) in VBACs. In this study, misoprostol was used only during the last year (1996), meaning that uterine ruptures in prior years most likely resulted from prostaglandin E2. This led to an ACOG Committee Opinion in April 2002 that discourages the use of all prostaglandins "for cervical ripening or the induction of labor in women attempting VBAC."
ACOG is still recommending VBAC as an option for most patients. The risk to most patients attempting VBAC is 0.5% to 1% for uterine rupture in patients with 1 prior low transverse cesarean. The key is to offer VABC to the correct patients and to select out patients at a higher risk of uterine rupture, such as those with multiple cesarean deliveries. A recent study showed that interdelivery intervals of up to 18 months may also be a risk factor for uterine rupture in patients undergoing VBAC. This study found that women with indelivery intervals of up to 18 months were 3 times as likely to have a symptomatic uterine rupture.
The question of whether written consent should be required for VBAC was raised. Dr. Socol does not believe that written consent is needed. However, the physician needs to provide his/her patient with a clear explanation of the possible risks and obtain verbal informed consent and should note that this was obtained in the chart. However, a written informed consent is prudent. There are now Web sites dealing with VBAC, which both physicians and patients can access. At VBAC.com, examples of written consent for VBAC can be reviewed.
Medscape Ob/Gyn. 2002;7(1) © 2002 Medscape
Cite this: Highlights in Obstetrics From the 50th Annual Meeting of The American College of Obstetricians and Gynecologists - Medscape - Jun 12, 2002.