Nonsurgical Management of Interstitial Pregnancies: Feasibility and Predictors of Treatment Failure.

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. PATIENTS: All women who were admitted to and treated for interstitial pregnancy at our center between 2011 and 2019. INTERVENTIONS: The 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. Nonsurgical (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 pregnancy were identified. There were high rates of pregnancy achieved by in vitro fertilization (45.9%) and a history of ipsilateral salpingectomy (43.2%) among these patients. At presentation, the mean age of the study cohort was 34.76 years, and the median ß-human chorionic gonadotropin level was 3853.0, and median gestational age was 7.0, respectively. The nonsurgical management success rate was 70.0%. Uterine rupture occurred during treatment in 5 cases (16.6%). 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, 1 of which was a recurrent interstitial pregnancy. The median interpregnancy interval was 8.1 months, and all but 3 pregnancies reached third trimester and resulted in a live birth, with an overall 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. CONCLUSION: Successful nonsurgical 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.