Risk Factors and Stratification Analysis of Cesarean Scar Pregnancy in Women with Cesarean Scar Diverticulum

To identify risk factors for cesarean scar pregnancy (CSP) in women with cesarean scar diverticulum (CSD) and develop a prediction model with risk stratification.

This retrospective study included 398 women with CSD and subsequent intrauterine pregnancy (82 CSP; 316 non-CSP). Clinical and sonographic variables were compared. Independent predictors from multivariable logistic regression were used to construct a nomogram. Model performance was assessed using ROC, calibration, decision curve analysis, and bootstrap validation. Risk groups were defined by tertiles of predicted probability.

Compared with controls, the CSP group had larger niche length and depth, thinner residual myometrium, shorter cesarean interval, and lower early log(hCG) and progesterone (all p < 0.05). Independent predictors were cesarean interval (OR = 0.812), niche length (OR = 1.235), niche depth (OR = 2.129), residual myometrium thickness (OR = 0.326), log(hCG) (OR = 0.445), and progesterone (OR = 0.830). The model showed excellent discrimination (AUC = 0.970, 95% CI: 0.954-0.983). CSP incidences were 0.0%, 0.8%, and 60.9% in the low-, medium-, and high-risk groups, respectively.

Morphological defect severity, short interpregnancy interval, and low early-pregnancy hormone levels were associated with CSP risk in women with CSD. The model may support early risk stratification and clinical management.