Clinical Question

Is misoprostol (Cytotec) alone associated with a high rate of success when used for first-trimester abortion of a viable pregnancy?

Bottom Line

Misoprostol alone was associated with a nearly 80% success rate in the first trimester of pregnancy on meta-analysis. The best associations were with 800-mcg dosing [corrected], three or more doses, non-oral route of administration, moistening of tablets before vaginal insertion, and a delay of three to seven days after completion of the misoprostol regimen before the decision to surgically evacuate. The safety of misoprostol alone was demonstrated by a rate of hospitalization and/or transfusion of less than 1%. (Level of Evidence = 2a)

Synopsis

This is an updated meta-analysis of misoprostol alone for abortion in the first trimester of pregnancy. Selected studies included women with viable pregnancies of variable gestational age limit, ranging from 42 to 98 days, nearly universally determined by ultrasonography. The meta-analysis included 42 studies with 53 study groups and 13,573 women. A total of 12,829 women were included in the analysis after the exclusion of 744 who were lost before outcomes were known (5%). There were multiple regimens, with dosing from 200 mcg to 800 mcg. [corrected] The most common dose was 800 mcg (n = 40 groups, 92% of women) [corrected]; the most common route of administration was vaginal (n = 38 groups, 81% of women). Most women were instructed to take no more than three doses within 48 hours. After one or more required doses, women in 35 groups (38% of women) could use additional doses, up to a maximum of six doses over 14 days. Across all studies, the meta-analytic estimate of the rate of women who underwent subsequent surgical evacuation was 22.0% (95% CI, 18.8% to 25.5%). The authors analyzed heterogeneity across studies and identified several factors associated with higher risk of surgical evacuation. They demonstrated a linear trend (P < .001) with the 800-mcg dosing being approximately one-fourth the risk of the 200-mcg dosing. [corrected] Oral administration was associated with a threefold higher risk compared with vaginal, buccal, or sublingual administration. Surgery was less common when tablets were moistened before vaginal insertion (odds ratio = 0.46; 0.35 to 0.60). Surgery also declined with allowed number of doses, duration of dosing (linear trend P ≤ .01 in each case). It was also less frequent when the decision to perform surgery was delayed three to seven days after treatment (odds ratio = 0.55; 0.31 to 0.96). Safety was demonstrated by the rare need for hospitalization (n = 14 women) or transfusion (n = 12). The meta-analytic estimate for either was 0.7% (0.4% to 1.0%). No women died.

Study design: Meta-analysis (other)

Funding source: Government

Allocation: Concealed

Setting: Various (meta-analysis)

Reference: Raymond EG, Harrison MS, Weaver MA. Efficacy of misoprostol alone for first-trimester medical abortion: a systematic review. Obstet Gynecol. 2019;133(1):137–147.