Outcome of cesarean scar ectopic pregnancy continued to viability: data from the international cesarean scar ectopic pregnancy registry

Background Cesarean scar ectopic pregnancy is a rare but serious complication of a prior cesarean section, in which the gestational sac implants within the previous uterine cesarean scar. Cesarean scar ectopic pregnancy carries a substantial risk of severe maternal morbidity, including life-threatening hemorrhage and hysterectomy. Objective The aim of this study is to describe the course of cesarean scar ectopic pregnancies that were managed expectantly and identify which ultrasound findings were associated with peripartum hysterectomy. Study Design An international registry was established to collect ultrasound and clinical data on diagnosis and management of cesarean scar ectopic pregnancy. Data are stored anonymously on a digital secure platform. This study included first-trimester, live cases that were managed expectantly or in which the patient declined pregnancy termination. Numbers of cases reaching viability, developing placenta accreta spectrum, and requiring peripartum hysterectomy were collected. Twenty-one centers across 13 countries contributed data for this specific analysis. Descriptive statistical methods were applied. Results Between August 29, 2018 and December 31, 2023, 708 cases were recorded, of which 593 were excluded due to pregnancy termination or nonviability. Of the remaining 115 cases, 38 (33.0%) resulted in pregnancy loss between 13+0 and 22+6 weeks, while 77 (67.0%) progressed to ≥23+0 weeks. Live births occurred in 77/115 (67.0%) cases. A total of 50/115 (43.5%) women underwent peripartum hysterectomy, including 7/115 (6.1%) before 23 weeks. A first-trimester residual myometrial thickness of less than 2.5 mm identified 80% (16/20) of women requiring peripartum hysterectomy with a sensitivity of 64%, specificity of 75%, and positive predictive value of 76%. Enhanced subplacental vascularity in the scar area was significantly more frequent in the hysterectomy group in 25/29 cases (86.2%) compared to those who retained their uterus with 13/22 cases (59.1%) (odds ratio, 4.13; 95% confidence interval, 1.09–18.4; P =.04). Conclusion Expectant management of cesarean scar ectopic pregnancy carries a substantial risk of second-trimester loss and peripartum hysterectomy. A residual myometrial thickness <2.5 mm and enhanced subplacental vascularity at first-trimester ultrasound are associated with an increased risk of hysterectomy. These findings underscore the importance of early and detailed ultrasound evaluation to identify high-risk cases, guide patient counseling, and optimize management strategies to mitigate maternal morbidity.