Uterine Rupture During VBAC Trial Of Labor: Risk Factors and Fetal Response

Nancy O'Brien-Abel, RNC, MN


J Midwifery Womens Health. 2003;48(4) 

In This Article

Risk Factors for Uterine Rupture

Several factors complicate the evaluation of risk factors for uterine rupture during VBAC-TOL. First, uterine rupture is a relatively rare event, requiring large sample sizes to identify significant statistical associations between various risk factors and uterine rupture. Most studies reported in the literature are small, making interpretation of results difficult. Second, randomized controlled trials are scarce in the VBAC literature. The majority of studies are observational series that used a case-control or cohort study design. Third, most studies define uterine rupture as a defect that involves the entire uterine wall that is symptomatic and requires surgical intervention, whereas uterine dehiscence is defined as asymptomatic scar separation or thinning that does not require intervention. However, the definition of uterine rupture varies slightly from study to study.

Although the overall rate of uterine rupture in women attempting VBAC-TOL is quoted to be less than 1%, women who elect a repeat cesarean birth without labor still have a uterine rupture risk of 0.03% to 0.2%.[9,10,11,12] Among those women attempting VBAC-TOL, rates of uterine rupture vary significantly, depending on associated risk factors ( Table 1 ). Characteristics in a woman's obstetric history (type of uterine scar, single-layer versus double-layer uterine closure, number of prior cesarean births, number of prior vaginal births, interdelivery interval, maternal age, maternal fever following cesarean), in addition to factors related to current labor management (induction or augmentation with prostaglandins and/or oxytocin), have been found to significantly influence uterine rupture rates during VBAC-TOL. Characteristics of questionable significance, such as macrosomia and postdate pregnancy, will not be discussed in this article; however, they are presented in an excellent review by Lieberman.[24]


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