Objective: To evaluate whether removal of a double-balloon device for cervical ripening for 6 compared with 12 hours in women with an unfavorable cervix will result in a shorter time to delivery, similar cervical ripening, and without affecting cesarean delivery rate.
Methods: In a prospective randomized trial, cervical ripening was performed using a double-balloon device. Women were randomized to removal of the device after 6 compared with 12 hours. Primary outcome was time to delivery. Secondary outcomes included mode of delivery, Bishop score, and maternal and neonatal adverse outcomes. A sample size of 100 nulliparous and 100 parous women was required assuming a 95% CI, power of 80%, and mean decrease of 6 hours to delivery between the groups.
Results: From March 2017 through February 2019, 688 women were screened, 243 were found eligible, and 197 were randomized as follows: nulliparous cohort (n=101): removal after 6 hours (n=48) compared with removal after 12 hours (n=53); parous cohort (n=96): removal after 6 hours (n=49) compared with removal after 12 hours (n=47). Insertion-to-delivery interval was significantly shorter in the 6-hour group for both nulliparous (25.6±12.8 hours vs 31.4±15.2 hours, P<.04; mean difference 5.8, 95% CI 0.2-11.3), and parous cohorts (18.0±6.8 hours vs 22.6±8.2 hours, P=.003; mean difference 4.7, 95% CI 1.6-7.7). Bishop score change and cesarean delivery rate were similar between groups regardless of parity. The 12-hour group in the combined cohort was associated with higher rates of maternal intrapartum fever (2% vs 10%, P=.02; odds ratio 5.3, 95% CI 1.1-24.8).
Conclusion: Insertion-to-delivery interval is shorter after 6 compared with 12 hours for both nulliparous and parous women. Cervical ripening with a double-balloon device may be achieved in 6 hours. The longer time was associated with a higher rate of intrapartum fever. Six hours should be considered as standard placement time for double-balloon catheters.
Clinical trial registration: ClinicalTrials.gov, NCT03045939.