Cervical balloon catheter vs Dilapan-S for outpatient cervical ripening: a randomized controlled trial

Abstract

Background: As labor induction increases in the United States, safe and effective outpatient cervical ripening has been explored as a method to decrease the inpatient time burden. However, the most effective method for outpatient mechanical cervical ripening remains unclear.

Objective: This study aimed to evaluate whether Dilapan-S is noninferior to a cervical balloon for outpatient cervical ripening based on the change in Bishop score.

Study design: This single-blind randomized controlled trial was conducted at a single tertiary hospital. Term patients, both nulliparous and multiparous, aged 18 to 50 years with a singleton cephalic fetus and no previous cesarean delivery who were scheduled for outpatient cervical ripening per preexisting hospital policy were eligible. Participants were randomized to single-balloon cervical ripening with a Cook catheter with 60 mL in the intrauterine balloon or placement of 3 to 5 Dilapan-S hydroscopic dilators and were discharged. Upon returning to the hospital, the cervical ripening agent was removed, a blinded cervical examination was performed, and the participants completed a satisfaction survey. Further labor induction was performed as per the obstetrical provider. The primary outcome was change in Bishop score. The secondary outcomes included patient satisfaction, mode of delivery, labor induction time, adverse maternal and neonatal outcomes, and cervical ripening failure composite (failure to place a randomized cervical ripening agent, premature rupture of membranes before a scheduled return to the hospital, significant vaginal bleeding, or need for further cervical ripening after the initial agent is removed). This study had 80% power to show noninferiority in change in Bishop score, with a margin of 2 and a standard deviation of 3.

Results: From May 2022 to June 2023, 80 participants were randomized, with no difference in baseline demographic data, starting dilation, or Bishop score. Of note, 70% of the participants in each arm were nulliparous. There was no difference in change in Bishop score between Dilapan-S and the cervical balloon catheter (median change: 3.0 [interquartile range, 2.0-5.0] vs 3.0 [interquartile range, 2.0-4.5], respectively; P=.91). There was no difference in the time to delivery, mode of delivery, or maternal or neonatal outcomes. Compared with participants randomized to a cervical balloon catheter, those randomized to Dilapan-S were more satisfied with their experience than (satisfaction scale of 0-10; median: 8 [interquartile range, 5-9] vs 9 [interquartile range, 8-10], respectively; P<.01) and were less likely to experience cervical ripening failure (18 (45.0%) vs 7 (17.5%), respectively; P<.01).

Conclusion: Dilapan-S was noninferior to a cervical balloon catheter for outpatient cervical ripening based on the change in Bishop score. The participants were more satisfied with Dilapan-S and less likely to experience cervical ripening failure than with a cervical balloon catheter with single-balloon inflation. El resumen está disponible en Español al final del artículo.

Keywords: Bishop score; Dilapan-S; balloon catheter; cervical ripening; induction; labor; mechanical; outpatient.