A Cochrane review included 7 studies with a total of 2 508 subjects. The sample sizes of individual studies were mostly small. Four different interventions were compared (prostaglandins alone, mifepristone alone, and mifepristone/misoprostol and methotrexate/misoprostol versus vacuum aspiration). The rate of abortions not completed with the intended method was statistically significant higher in the group receiving prostaglandins than with vacuum aspiration (2.7, 95% CI 1.1 to 6.8). There were no data on the most common medical (mifepristone/misoprostol) and surgical abortion available to be included in the review.
Duration of bleeding was longer in the medical abortion groups compared to vacuum aspiration. There was only one major complication (uterine perforation) in one trial in the surgical group. There was no difference between the groups for ongoing pregnancies at the time of follow-up or pelvic infections. No data on acceptability, side effects or women's satisfaction with the procedure were available for inclusion in the review.
Comment: The quality of evidence is downgraded by inconsistency (heterogeneity in interventions and outcomes), by indirectness (need for trials to address the efficacy of currently used medical methods), and by imprecise results (limited study size for each comparison).