A novel scoring model to predict massive hemorrhage during dilatation and curettage following focused ultrasound ablation surgery in patients with type 2 cesarean scar pregnancy

To develop a predictive model for assessing massive hemorrhage risk during dilatation and curettage (D&amp;C) after focused ultrasound ablation surgery (FUAS) in Type 2 cesarean scar pregnancy (CSP) patients. A retrospective analysis of 405 Type 2 CSP patients treated at Hunan Maternal and Child Health Hospital (2018–2023) was conducted. Multivariable logistic regression identified independent risk factors, and a nomogram was constructed. Model performance was evaluated using AUC, calibration curves, and decision curve analysis (DCA). Ten-fold cross-validation was performed, and external validation was conducted on 327 patients. Independent risk factors included gestational sac maximum diameter (OR 1.11, 95% CI: [1.07–1.15], <i>p</i> &lt; 0.001), GS blood flow US grade 3 (OR 9.96, 95% CI: [2.65–40.10], <i>p</i> &lt; 0.001), and FUAS-curette time &gt;24 h (OR 17.57, 95% CI: [3.88–84.48], <i>p</i> &lt; 0.001). C-scar thickness and HCG levels were also included in the model as clinically significant factors. The model showed high discriminative ability (AUC 0.910, 95% CI: 0.867–0.953) and was validated through 10-fold cross-validation (mean AUC 0.838). External validation confirmed its robustness (AUC 0.812, 95% CI: 0.742–0.881). Calibration curves and DCA confirmed its accuracy and clinical utility. The predictive model effectively assesses hemorrhage risk in Type 2 CSP patients post-FUAS, offering valuable clinical utility.