Laminaria vs. vaginal misoprostol for cervical preparation before second-trimester surgical abortion: a randomized clinical trial

Objective: To compare the efficacy and tolerability of vaginal misoprostol and laminaria for cervical preparation before second-trimester surgical abortion.

Study design: We performed a prospective, randomized trial comparing midnight administration of misoprostol 600 mcg vaginally to midnight placement of laminaria, before surgical abortions among women at 13-20 weeks of gestation. The primary outcome was preoperative cervical dilation. Secondary outcomes were the need for further dilation, procedure duration and difficulty, immediate complications and side effects.

Results: Eighty-four women were randomized, with a median gestational age of 16.5 weeks. The mean time interval between misoprostol and laminaria placement and dilatation and evacuation initiation was 11.0±2.9 and 11.2±2.0h, respectively (p=.17). Cervical dilation was not greater in the laminaria group as compared to the misoprostol group (12.8 vs. 12.4mm, respectively; p=.32). No difference was demonstrated regarding the need for additional dilation or the difficulty of the procedure. Procedures performed after laminaria insertion were 1 min longer (median 11 vs. 10 min, p=.04). Participants found laminaria placement more uncomfortable than vaginal misoprostol placement. Other than pain, additional side effects occurred only in the misoprostol group, primarily nausea and vomiting. One participant in the misoprostol group experienced fetal expulsion during the night before the intended procedure.

Conclusion: Either vaginal misoprostol or laminaria provides adequate dilation for second-trimester surgical abortion. Laminaria causes more pain at insertion and misoprostol causes more side effects.

Implications statement: We found that cervical preparation in an inpatient setting for approximately 11h with misoprostol 600 mcg vaginally is comparable to 11h of laminaria. However, given the potential for spontaneous expulsion and more side effects with misoprostol, laminaria is likely a better general option in such a setting.