Ultrasound parameters for predicting high bleeding risk and efficacy of uterine artery embolization in gestational sac-type cesarean scar pregnancy: a retrospective single-center study.

BACKGROUND: Cesarean scar pregnancy (CSP) is a life-threatening ectopic pregnancy that can cause uterine rupture and severe hemorrhage. Uterine artery embolization (UAE) combined with curettage effectively reduces intraoperative blood loss, but the procedure is invasive and lacks objective preoperative risk stratification. The purpose of this study was to evaluate the efficacy of UAE and determine whether ultrasound parameters can help identify patients at high risk of bleeding, thereby informing clinical decision-making.

METHODS: A total of 161 patients with gestational sac-type CSP treated by either direct ultrasound-guided curettage or curettage after UAE were retrospectively enrolled. Based on the treatment modality, they were divided into a direct ultrasound-guided curettage group (non-UAE group; n=63) or a post-UAE curettage group (UAE group; n=98). Propensity score weighting was applied to estimate the causal effect of UAE on intraoperative blood loss. High-bleeding risk was defined as intraoperative blood loss ≥100 mL. Optimal cutoff values for ultrasound parameters were identified via receiver operating characteristic (ROC) analysis, and the predictive performance of the combined models was assessed.

RESULTS: Propensity score weighting analysis showed that UAE reduced intraoperative blood loss by 41.83 mL as compared with direct ultrasound-guided curettage (P=0.007), and the absolute risk of major bleeding decreased from 29.4% to 3.7% (P<0.001). The area under the curve (AUC) of both maximum gestational sac diameter and gestational sac volume for predicting high-bleeding risk was 0.752, with optimal cutoffs of 2.25 cm and 7.78 cm3, respectively. Adding myometrial thickness and blood flow grade to maximum gestational sac diameter alone increased the AUC from 0.752 to 0.764. The weighted kappa for interobserver agreement of blood flow grading was 0.787 [95% confidence interval (CI): 0.717-0.856], indicating good consistency.

CONCLUSIONS: UAE was associated with a reduced risk of bleeding during curettage for gestational sac-type CSP. Gestational sac size was the main predictor of bleeding risk; myometrial thickness and blood flow grade showed a tendency toward higher risk but did not reach statistical significance in this cohort. Early detection and timely management are crucial for reducing bleeding risk and improving prognosis.