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 beta hCG 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 beta hCG 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 beta hCG and sonographic endometrial stripe is suggested to define high risk patients for failed medical abortion.