Risk factors associated with failure of treatment for cesarean scar pregnancy

Objective: To identify risk factors associated with treatment failure among women with cesarean scar pregnancy (CSP). Methods: In a retrospective study, the medical records of patients with CSP treated at National Taiwan University Hospital, Taipei, Taiwan, from 1994 to 2015 were reviewed. The women were managed primarily with hysterotomy, evacuation, or methotrexate. Receiver operating characteristic (ROC) curve analysis and logistic regression analysis were used to evaluate the factors associated with treatment failure. Results: Among 90 patients, 44 underwent hysterotomy, 18 underwent evacuation, and 28 received methotrexate. The success rates were 100% (44/44) for hysterotomy, 83% (15/18) for evacuation, and 57% (16/28) for methotrexate (P<0.001). ROC curve analysis indicated that a pregnancy length of 8 weeks and a mean sac diameter (MSD) of 4 cm were both predictive of failure of treatment by primary evacuation and methotrexate. In multivariate logistic regression analysis, an MSD of 4 cm or more was the only independent risk factor for treatment failure (odds ratio 68.99, 95% confidence interval 6.27-759.60; P=0.001). Conclusion: Primary hysterotomy was suitable for treatment of CSP of any size. Failure of primary evacuation or methotrexate usually occurred when the MSD was larger than 4 cm.