297: High-dose misoprostol with subsequent foley versus low-dose misoprostol with concurrent foley for cervical ripening

Abstract

A prominent trial showed low-dose misoprostol with concurrent Foley for cervical ripening increased the likelihood of vaginal delivery and shortened the median time to delivery when compared to either method alone, prompting many institutions to adopt this protocol. Our study aimed to address differences in labor outcomes with low-dose misoprostol and concurrent Foley versus high-dose misoprostol and subsequent Foley. This was a retrospective before-and-after study of nulliparous women with non-anomalous, term, singletons delivered at the University of California San Francisco (UCSF) in two separate two-year periods before and after changes in UCSF’s IOL protocol. In May 2017, the term IOL protocol changed from 50-100 mcg PO every 4 hours with subsequent Foley to 25 mcg PO every 2 hours with concurrent Foley. The primary outcome was time from first misoprostol dose to delivery. The Kruskal-Wallis test was used to compare median values, and chi-squared tests were used to compare proportions. 1,496 women met the inclusion criteria. Comparing the high-dose group (n = 698) to the low-dose group (n = 798), we found no statistically significant differences in time to delivery (29.1 vs 29.9 hr, P = 0.689), rate of cesarean delivery (30% vs 26%, P = 0.086), or cesarean delivery for fetal indications (11% vs 8%, P = 0.145). Among vaginal delivers, there was similarly no difference in time to delivery (26.9 vs 27.0 hr, P = 0.893). Although the low-dose cohort had a lower cumulative misoprostol dose (100 mcg vs 150 mcg, P < 0.001), this group had a higher number of misoprostol administrations (4 vs 2, P < 0.001). Protocols using high-dose misoprostol with subsequent Foley and low-dose misoprostol with concurrent Foley did not differ in time to delivery, time to vaginal delivery, or likelihood of vaginal delivery. In the absence of a superior clinical method for cervical ripening a shared-decision making model, incorporating patient preference, may be applied regarding timing of Foley catheter placement and dosing of misoprostol.