375: Is Foley catheter use during TOLAC associated with uterine rupture?

Abstract

Uterine rupture rates are 3 times higher in women who undergo an induction of a trial of labor after cesarean section (TOLAC). As safe pharmacologic cervical ripening agents are limited, mechanical dilation with a Foley catheter is often used in clinical practice, but the association between mechanical ripening and uterine rupture in patients undergoing TOLAC is not clearly delineated. We sought to assess whether use of a Foley catheter in women undergoing a TOLAC is associated with an increased risk of uterine rupture. We performed a secondary analysis of the Maternal-Fetal Medicine Unit’s (MFMU) Cesarean Section (CS) Registry, a prospective observational cohort study. We included women with a history of ≤2 low transverse CS who underwent induction at 324 weeks of gestational age with a live singleton fetus without major anomalies. We excluded those who received prostaglandins or laminaria. We performed multinomial logistic regression, calculating adjusted relative risk (aRR) ratios. Relevant confounders accounted for included prior vaginal delivery, pregnancy-induced hypertension (PIH), chorioamnionitis, and cervical effacement and dilation on admission. 2564 women were eligible. Foley catheter did not increase the risk of uterine rupture in TOLAC (aRR 2.02, p=0.19). Similarly, uterine scar dehiscence was also not associated with Foley catheter use (aRR 1.32, p=0.67). Chorioamnionitis and PIH were significantly associated with increased risk of uterine dehiscence only (aRR 7.40, p<0.01 and aRR 1.89, p=0.02, respectively). Our data suggest that the Foley catheter is a safe tool for mechanical dilation in women undergoing a TOLAC. While we noted a significant association between chorioamnionitis and PIH with uterine dehiscence, this may reflect an earlier decision to proceed with repeat CS in the setting of additional maternal comorbidities. Given the risks of prostaglandin use in TOLAC, our data can assist providers regarding the safety of a Foley catheter in this patient population.