Non-surgical management of interstitial pregnancies: feasibility and predictors of treatment failure

Abstract Study objectives To describe the management of interstitial pregnancies in a tertiary medical center, identify factors associated with treatment failure, and report subsequent pregnancy outcome. Design Retrospective cohort study. Setting Department of Gynecology in a tertiary medical center. Patiens All women who were admitted and treated for interstitial pregnancy between 2011-2019. Interventions Women were originally assigned to undergo expectant, medical or surgical treatment. The women's background and clinical data were compared according to initial treatment modality. Non-surgical (expectant and medical) management outcomes were analyzed to identify risk factors for treatment failure. Subsequent pregnancy outcomes were described separately. Measurement and main results Thirty-seven cases of interstitial pregnancies were identified. There were high rates of pregnancies achieved by in-vitro fertilization (45.9%) and a history of ipsilateral salpingectomy (43.2%) among these patients. At presentation, mean age of the study cohort was 34.76 and median βHCG level and gestational age were 3853.0 and 7.0, respectively. The non-surgical management success rate was 70.0%. A uterine rupture occurred during treatment in five (16.6%) cases. Gestational sac diameter significantly affected treatment failure ( P = .03), and a diameter >20 mm was observed in all cases of failed non-surgical treatment. Data on future fertility was available for 21 (58.3%) women: 13 (61.9%) had a subsequent pregnancy, one of which was a recurrent interstitial pregnancy. The median inter-pregnancy interval was 8.1 months and all but three pregnancies reached third trimester and resulted in a live birth, with a total cesarean delivery rate of 61.5%. None of the subsequent pregnancies were complicated by uterine rupture, and no serious adverse outcomes were noted in any of the subsequent intrauterine pregnancies that reached third trimester. Conclusions Successful non-surgical management of an interstitial pregnancy is feasible, although appropriate selection of cases is advised. A large gestational sac is a risk factor for treatment failure and should prompt surgical intervention. Subsequent pregnancies can generally be considered safe and with a favorable outcome.