Outpatient Compared With Inpatient Preinduction Cervical Ripening Using a Synthetic Osmotic Dilator: A Randomized Clinical Trial

To assess whether outpatient cervical ripening with a synthetic osmotic dilator shortens the length of hospital stay in term pregnancies undergoing labor induction. METHODS: Pregnant participants scheduled for labor induction at term with unfavorable cervix (less than 3-cm dilated and less than 60% effaced) and not requiring inpatient maternal or fetal monitoring were consented, and synthetic osmotic dilator rods were inserted on the day of scheduled induction. After reassuring fetal heart tracing, patients randomized to the outpatient group were asked to return 12 hours after insertion or sooner if needed. Those randomized to the inpatient group remained in the hospital. After the first round of ripening, additional ripening, oxytocin, and labor management were left up to the clinical health care professionals. The primary outcome was the proportion of participants with hospital stays longer than 48 hours. We estimated that a sample size of 338 would provide 85% power to detect a 30% difference between groups. RESULTS: From November 2018 to November 2021, 339 participants were randomized (171 inpatient, 167 outpatient, one withdrawal). Four patients in the outpatient group were admitted before12 hours for suspected labor and rupture of membranes, and 19 in the inpatient group had the device removed before 12 hours. The proportion of participants with hospital stays longer than 48 hours was lower in the outpatient group compared with the inpatient group (89 [53%] vs 152 [89%], relative risk [RR] 0.60, 95% CI 0.52–0.70). Patients in the outpatient group had a shorter total length of stay and time from admission to active labor. They were more likely to have a vaginal delivery within 24 hours of admission and were less likely to receive analgesics during ripening. Route of delivery and other maternal and neonatal outcomes were not significantly different between groups. CONCLUSION: Outpatient cervical ripening with a cervical osmotic dilator decreased hospital stay compared with inpatient ripening, without significant adverse outcomes. FUNDING SOURCE: Medicem Technology s.r.o., Czech Republic. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT03665688.