Establishment and validation of a nomogram model for the risk of cesarean scar pregnancy

Objective:To analyze the risk factors of cesarean scar pregnancy(CSP)in women after cesarean section and establish an individualized nomogram model for predicting its occurrence risk.Methods:Clinical data of 1, 566 pregnant women who underwent cesarean section in our hospital from January 2015 to September 2022 and subsequently became pregnant again were retrospectively analyzed, including 236 cases with CSP (CSP group)and 1, 330 cases without CSP(non-CSP group).The research subjects were randomly divided into the modeling group(70%)and the validation group(30%).Multivariate logistic regression analysis was used to analyze the influencing factors of CSP, and the nomogram was drawn.The receiver operating characteristic (ROC) curve was used to determine the prediction ability of the model and the calibration plot was drawn to evaluate the calibration ability of the model.Results:There were significant differences in pregnancy times, parity times, abortion times, cesarean section times, vaginal bleeding in early pregnancy and uterine position between CSP group and non-CSP group (all P< 0.05).Multivariate logistic regression analysis showed that parity ≥3 times (OR=2.056, 95% CI: 1.032-3.947), parity=2 times (OR=6.795, 95% CI: 4.689-9.905), abortion ≥2 times (OR=2.582, 95% CI: 1.848-3.619), and vaginal bleeding in early pregnancy (OR=10.722, 95% CI: 7.675-15.125) were independent risk factors for CSP; retroflexion of uterus(OR=0.479, 95%CI:0.319-0.706)was an independent protective factor for CSP(all P< 0.05).The area under the ROC curve (AUC) was 0.854; the calibration curve of the model was close to the standard curve, and the Brier score was 0.089.Conclusion:Parity ≥2 times, abortion ≥2 times, vaginal bleeding in early pregnancy and retroflexion of uterus are the influencing factors of CSP.It is feasible to predict the occurrence of CSP based on the nomogram, and it has reference significance for clinical intervention decision-making.