Risk factors for unsuccessful medical abortion with mifepristone and misoprostol

Background. The aim of this study was to determine the effectiveness of medical abortions with mifepristone and misoprostol following the approval of medical abortion in Israel. Methods. A retrospective review of 377 consecutive medical records at an ambulatory care unit of a university medical centre was performed, screening all women undergoing medical abortion with mifepristone and misoprostol. Transvaginal ultrasonographic study and serum βhCG measurement were performed 14-20 days after the procedure. The clinical outcome was defined as complete expulsion of intrauterine contents with (failed group) or without (successful group) surgical intervention. Results. Surgical intervention was performed in 7.4% of patients. Residual products of conception were confirmed in 89%. Older age, previous spontaneous abortions, multigravidity, and earlier follow-up visit were independently associated with unsuccessful medical abortion. Significant differences were found in mean serum βhCG and mean endometrial thickness in the successful versus failed procedure groups. Conclusions. Medical termination of pregnancy with mifepristone and misoprostol is >90% effective. High risk group for failure of the procedure can be characterised. An algorithm of follow up using follow-up visit date, serum βhCG and sonographic endometrial stripe is suggested to define high risk patients for failed medical abortion.