Objective: To assess the role of cervical length when predicting vaginal delivery after a previous cesarean section (CS) in women with low Bishop score following the use of a double-balloon catheter for induction of labor (IOL).
Methods: A prospective, longitudinal study was conducted at a large teaching hospital in Santiago to recruit pregnant women at term with a previous CS and Bishop score ≤6 for IOL with a double-balloon catheter. The device was maintained for up to 24 h and the patient continued IOL with oxytocin only if the Bishop score was >6. Demographic and clinical variables were recorded and compared against vaginal delivery as the primary outcome. Multivariate logistic regression analysis was used to compare perinatal demographic and clinical variables in women achieving vaginal delivery versus those having a repeat CS.
Results: The final cohort included 40 pregnant women. Women achieving vaginal delivery (n = 17, 42.5%) had statistically significant differences in mean cervical length (24.8 mm versus 33.4 mm, respectively; p = .006), median Bishop score after removing the double-balloon catheter (11 versus 7, respectively; p = .005), and mean interval between double-balloon catheter placement and vaginal delivery or the decision to perform a CS (17.4 h versus 23.6 h, respectively; p = .03). Backward stepwise selection revealed an odds ratio of 0.90 (95% confidence interval = 0.82-0.98) for cervical length and a receiver operating characteristic curve area of 0.73.
Conclusion: Cervical length, as determined by transvaginal sonography, proved to be effective in predicting vaginal delivery in women with a previous CS and low Bishop score following the use of a double-balloon catheter for IOL.
Keywords: Cervical length; double-balloon catheter; induction of labor; previous cesarean section; transvaginal ultrasound; vaginal delivery.