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Clinical Obstetrics

Poster Session 3

(681) Mifepristone pretreatment for second trimester induction, to wait or not to wait?

Wednesday, February 14, 2024
8:30 AM – 10:00 AM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level
Objective: Mifepristone is administered 24 hours (hrs) before initiation of nonviable induction of labor in the second trimester (NIST) to reduce time from induction start to delivery. NIST is often performed in emergent cases, where expeditious care is vital. We hypothesized that mifepristone pretreatment compared misoprostol only would reduce time to delivery, time in labor, and need for dilation and curettage (D&C).

Study Design: We conducted a retrospective chart review of patients with previable PPROM, IUFD, fetal anomalies, and maternal contraindications to pregnancy presenting at a single tertiary academic center for NISTs from 2018 to 2022. We compared the time to delivery, in labor, and need for D&C between those who received misoprostol only or mifepristone pretreatment. Stratification by time from first misoprostol or mifepristone pretreatment and an analysis excluding PPROM patients were performed.

Results: Of 103 patients, 37 received mifepristone pretreatment, while 66 received misoprostol alone, and 56% of patients underwent NIST for IUFD. Comparing time from first NIST medication (misoprostol only or mifepristone pretreatment) to completion of delivery, there was a statistically significant increase in time when mifepristone was given (11.0 hrs [7.4, 20.0] vs. 34.4 hrs [28.7, 45.3], p< 0.001). There was a nonsignificant decrease in labor time (p=0.91) when mifepristone pretreatment time was excluded without a difference in need for D&C (12% vs. 13.5%, p=1.00). Stratification by time from no pretreatment or mifepristone pretreatment (< 24hrs or >24hrs) showed no difference in time in labor; but there was a statistically significant difference in total time from first medication to delivery (Table). Exclusion of PPROM patients did not change the results.

Conclusion:

Mifepristone pretreatment increases the total time from first medication to delivery without a significant difference in labor duration. Our data suggests shortening the time from mifepristone to first dose of misoprostol administration could further expedite NIST care.