Effectiveness and safety of misoprostol-only for first-trimester medication abortion: An updated systematic review and meta-analysis

Objectives: This study aimed to update our 2019 systematic review of data on the effectiveness and safety of misoprostol-only for first-trimester abortion. Study design: We searched PubMed on December 18, 2022, to find published articles describing the outcomes of treatment with misoprostol-only for abortion of viable intrauterine pregnancy at <= 91 days of gestation. From each article identified, two authors independently abstracted relevant data about each group of patients treated with a distinct regimen. We assessed the risk of bias using four defined indicators. We estimated the proportion of patients with treatment failure using meta-analytic methods as well as the proportion hospitalized or transfused after treatment. We examined associations between treatment failure and selected characteristics of the groups. Results: We identified 49 papers with 66 groups that collectively included 16,354 evaluable patients, of whom 2960 (meta-analytic estimate 15%, 95% CI 12%, 19%) had treatment failures. Of 9228 patients assessed for ongoing pregnancy after treatment, 521 (meta-analytic estimate 6%, 95% CI 5%, 8%) had that condition. Failure risk was significantly associated with misoprostol dose, the total allowed number of doses, the maximum duration of dosing, and certain indicators of risk of bias. Among 11,007 patients allowed to take at least three misoprostol doses, the first consisting of misoprostol 800 mcg administered vaginally, sublingually, or buccally, the meta-analytic estimate of the failure risk was 11% (95% CI 8%, 14%). At most, 0.2% of 15,679 evaluable patients were hospitalized or received transfusions. Conclusions: Although some studies in this updated review were adjudicated to have a high risk of bias, the results continue to support the key conclusion of our 2019 analysis: misoprostol-only is effective and safe for the termination of first-trimester intrauterine pregnancy. Implications: Misoprostol-only is a safe and effective option for medication abortion in the first trimester if mifepristone is unavailable or inaccessible.