Routine vaginal examination to assess labor progress at 8 compared to 4 hours after early amniotomy following Foley balloon ripening in the labor induction of multiparas: a randomized trial

Abstract

BackgroundVaginal examination to monitor progress in labor is recommended at least every 4 hours but it can cause pain and embarrassment to women. Trial data is limited on the best intensity for vaginal examination. Vaginal examination is not needed for oxytocin dose titration after amniotomy has been performed and oxytocin infusion started. The Foley balloon commonly ripens the cervix without strong contractions; amniotomy and oxytocin infusion is usually required to drive labor. ObjectiveTo evaluate the first vaginal examination at 8 vs 4 hours after amniotomy-oxytocin following Foley ripening in multiparous labor induction. MethodsA randomized controlled trial was conducted from October 2021 to September 2022 in University Malaya Medical Center. Multiparas at term were recruited at admission for labor induction. Participants were randomized to a first routine vaginal examination at 8 or 4 hours after Foley balloon ripening and amniotomy. Titrated oxytocin infusion was routinely commenced after amniotomy to initiate contractions. The two primary outcomes were the time from amniotomy to delivery (non-inferiority hypothesis) and maternal satisfaction (superiority hypothesis). Data were analyzed with the Student t-test, Mann-Whitney U test, Chi square test (or Fisher exact test) as suitable for the data. Results204 women were randomized, 102 to each arm. Amniotomy to birth interval was mean±standard deviation 4.97±2.47 vs 5.79±3.17, mean difference -0.82, 97.5% CI (-1.72 to 0.08) hours p=0.041 (Bonferroni correction), which was non-inferior within the pre-specified 2 hour upper margin and maternal satisfaction score with allocated labor care was median[interquartile range] 9[8-9] vs 8[7-9] p=0.814 (11-point 0-10 NRS) for 8 vs 4 hours arms respectively. Oxytocin infusion to birth interval difference was also non-inferior within the 97.5% CI (-1.59 to 0.23) margin of 2 hours. Of the maternal outcomes, amniotomy to first vaginal examination intervals were 3.9±1.8 vs 3.4±1.3hours p=0.026 and number of vaginal examinations was 2[2-3] vs 3[2-3.25] p<0.001 for 8 vs 4 hours arms respectively. For the 8 hours arm, first vaginal examination was less likely to be as scheduled and more likely to be indicated by sensation to bear down (p<0.001) and epidural analgesia rate was lower 13/102 (12.7%) vs 28/102 (27.5%) RR 0.46 95% CI 0.26–0.84 p=0.009. Other outcomes of mode of delivery, indications for cesarean and delivery blood loss were not different. Neonatal outcomes were not different. ConclusionRoutine first vaginal examination at 8 hours compared to 4 hours is non-inferior for the time to birth but does not improve maternal satisfaction.