Universität zu Köln

Lukow, geb. Bangun, Ruth Sanny Malemna (2026). Sequential Use of Osmotic Dilators and Oral Misoprostol Versus Misoprostol Alone on Unfavorable Cervix. PhD thesis, Universität zu Köln.

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Abstract

Background: Several methods are available for cervical ripening in women with an unfavorable cervix, but there is still no international consensus regarding the optimal induction approach. Osmotic dilators offer a favorable safety profile and an option for outpatient cervical ripening. This study assessed whether an induction of labor with sequential osmotic dilators and misoprostol improves the induction-delivery-interval and other obstetric and neonatal outcomes compared to misoprostol alone.   Methods: This single-center prospective randomized controlled trial was conducted at Marienhospital Osnabrück, Germany, between July 2023 and February 2025. A total of 130 term pregnant women with an unfavorable cervix, defined as Bishop Score < 6, were randomized to either oral misoprostol alone or osmotic dilators followed by oral misoprostol if labor did not progress under induction with the osmotic dilators. In the study group, osmotic dilators were inserted for 18–24 hours, mainly in an outpatient setting. Both groups followed the same misoprostol protocol thereafter. The primary outcome was the induction-to-delivery interval. Maternal and neonatal outcomes were also evaluated.   Results: Sequential induction with osmotic dilators followed by misoprostol was comparably effective to misoprostol alone, particularly in nulliparous women. In this subgroup, induction-to-delivery interval was similar between the study and control groups (38.0 vs. 39.3 hours; p = 1.000). Rates of vaginal birth within 36 and 48 hours, as well as overall spontaneous vaginal delivery, were nearly identical. The combined approach significantly reduced the required misoprostol dose (median 100 μg vs. 200 μg; p < 0.001) and allowed outpatient cervical ripening in most cases. 25% of study participants achieved vaginal birth without requiring misoprostol at all. Caesarean section rates were lower in the combination group, although the difference was not statistically significant. Neonatal complications were low and comparable between groups. Among multiparous women, misoprostol alone was associated with a shorter induction-to-delivery interval. Conclusion: Sequential cervical ripening with osmotic dilators followed by misoprostol is a safe and effective alternative to misoprostol alone. It achieves comparable delivery outcomes, reduces the required misoprostol dosage, and supports outpatient cervical ripening without adverse maternal or neonatal effects.