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

BACKGROUND: Vaginal examination to monitor labor progress is recommended at least every 4 hours, but it can cause pain and embarrassment to women. Trial data are limited on the best intensity for vaginal examination. Vaginal examination is not needed for oxytocin dose titration after an amniotomy has been performed and oxytocin infusion started. The Foley balloon commonly ripens the cervix without strong contractions. Amniotomy and oxytocin infusion are usually required to drive labor. OBJECTIVE: This study aimed to evaluate the first vaginal examination at 8 vs 4 hours after amniotomy-oxytocin after Foley ripening in multiparous labor induction. STUDY DESIGN: A randomized controlled trial was conducted from October 2021 to September 2022 at the University Malaya Medical Center, Kuala Lumpur, Malaysia. 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 2 primary outcomes were the time from amniotomy to delivery (noninferiority hypothesis) and maternal satisfaction (superiority hypothesis). Data were analyzed using the Student t test, Mann-Whitney U test, and chi-square test (or Fisher exact test), as suitable for the data. RESULTS: A total of 204 women were randomized, 102 to each arm. Amniotomy to birth intervals were 4.97+2.47 hours in the 8-hour arm and 5.79+3.17 hours in the 4-hour arm (mean difference, -0.82; 97.5% con fidence interval, -1.72 to 0.08; P=.041; Bonferroni correction), which were noninferior within the prespeci fied 2-hour upper margin, and the maternal satisfaction scores (11 -point 0 -10 numerical rating scale) with allocated labor care were 9 (interquartile range, 8 -9) in the 8-hour arm and 8 (interquartile range, 7 -9) in the 4-hour arm ( P=.814). In addition, oxytocin infusion to birth interval difference was noninferior within the 97.5% con fidence interval (-1.59 to 0.23) margin of 1.3 hours. Of the maternal outcomes, the amniotomy to first vaginal examination intervals were 3.9+1.8 hours in the 8-hour arm and 3.4+ 1.3 hours in the 4-hour arm ( P=.026), and the numbers of vaginal examinations were 2.00 (interquartile range, 2.00 -3.00) in the 8-hour arm and 3.00 (interquratile range, 2.00 -3.25) in the 4-hour arm ( P<.001). For the 8-hour arm, the first vaginal examination was less likely to be as scheduled and more likely to be indicated by sensation to bear down ( P<.001), and the epidural analgesia rates were lower (13/ 102 participants [12.7%] in the 8-hour arm vs 28/102 participants [27.5%] in the 4-hour arm; relative risk, 0.46; 95% con fidence interval, 0.26 -0.84; P=.009). Other outcomes of the mode of delivery, indications for cesarean delivery, and delivery blood loss were not different. Neonatal outcomes were not different. CONCLUSION: Routine first vaginal examination at 8 hours compared with that at 4 hours was noninferior for the time to birth but did not improve maternal satisfaction.