Cesarean Scar Ectopic Pregnancy Clinical Classification System With Recommended Surgical Strategy
Authors: Ban Yanli , Shen Jia , Wang Xia , Zhang Teng , Lu Xuxu , Qu Wenjie , Hao Yiping , Mao Zhonghao , Li Shizhen , Tao Guowei , Wang Fang , Zhao Ying , Zhang Xiaolei , Zhang Yuan , Zhang Guiyu , Cui Baoxia 
Published: April 2023

OBJECTIVE:
To establish a new cesarean scar ectopic pregnancy clinical classification system with recommended individual surgical strategy and to evaluate its clinical efficacy in treatment of cesarean scar ectopic pregnancy.

METHODS:
This retrospective cohort study included patients with cesarean scar ectopic pregnancy in Qilu Hospital in Shandong, China. From 2008 to 2015, patients with cesarean scar ectopic pregnancy were included to determine risk factors for intraoperative hemorrhage during cesarean scar ectopic pregnancy treatment. Univariable analysis and multivariable logistic regression analyses were used to explore the independent risk factors for hemorrhage (300 mL or greater) during a cesarean scar ectopic pregnancy surgical procedure. The model was internally validated with a separate cohort. Receiver operating characteristic curve methodology was used to identify optimal thresholds for the identified risk factors to further classify cesarean scar ectopic pregnancy risk, and the recommended operative treatment was established for each classification group by expert consensus. A final cohort of patients from 2014 to 2022 were classified according to the new classification system, and the recommended surgical procedure and clinical outcomes were abstracted from the medical record.

RESULTS:
Overall, 955 patients with first-trimester cesarean scar ectopic pregnancy were included; 273 were used to develop a model to predict intraoperative hemorrhage with cesarean scar ectopic pregnancy, and 118 served as an internal validation group for the model. Anterior myometrium thickness at the scar (adjusted odds ratio [aOR] 0.51, 95% CI 0.36–0.73) and average diameter of the gestational sac or mass (aOR 1.10, 95% CI 1.07–1.14) were independent risk factors for intraoperative hemorrhage of cesarean scar ectopic pregnancy. Five clinical classifications of cesarean scar ectopic pregnancy were established on the basis of the thickness and gestational sac diameter, and the optimal surgical option for each type was recommended by clinical experts. When the classification system was applied to a separate cohort of 564 patients with cesarean scar ectopic pregnancy, the overall success rate of recommended first-line treatment with the new classification grouping was 97.5% (550/564). No patients needed to undergo hysterectomy. Eighty-five percent of patients had a negative serum β-hCG level within 3 weeks after the surgical procedure; 95.2% of patients resumed their menstrual cycles within 8 weeks.

CONCLUSION:
Anterior myometrium thickness at the scar and the diameter of the gestational sac were confirmed to be independent risk factors for intraoperative hemorrhage during cesarean scar ectopic pregnancy treatment. A new clinical classification system based on these factors with recommended surgical strategy resulted in high treatment success rates with minimal complications.