RESUMEN
Importance: Several medications have been used to achieve medical abortion in the first trimester of pregnancy. The most commonly used is the combination of mifepristone and misoprostol; however, different doses and routes of administration have been proposed. Objective: The aim of this study was to summarize published data on the effectiveness, adverse effects, and acceptability of the various combinations of mifepristone and misoprostol in medical abortion protocols in the first trimester of pregnancy. Evidence Acquisition: This was a comprehensive review, synthesizing the findings of the literature on the current use of mifepristone and misoprostol for first-trimester abortion. Results: The combination of mifepristone and misoprostol seems to be more effective than misoprostol alone. Regarding the dosages and routes, mifepristone is administered orally, and the optimal dose is 200 mg. The route of administration of misoprostol varies; the sublingual and buccal routes are more effective; however, the vaginal route (800 µg) is associated with fewer adverse effects. Finally, the acceptability rates did not differ significantly. Conclusions: Different schemes for first-trimester medical abortion have been described so far. Future research needs to focus on identifying the method that offers the best trade-off between efficacy and safety in first-trimester medical abortion.
