Diagnostic performance of combined ultrasound parameters, B-hCG, and estradiol in early caesarean scar pregnancy and their association with intraoperative bleeding during curettage.

Cesarean scar pregnancy (CSP), a serious complication following cesarean section, may increase the risk of massive intraoperative bleeding and hysterectomy due to the implantation of the gestational sac at the uterine scar site. This study employed a prospective cohort analysis to investigate the diagnostic value of ultrasound parameters combined with estrogen levels for CSP in early pregnancy and its correlation with intraoperative bleeding volume during curettage. A total of 98 patients with CSP and 92 healthy controls, admitted from April 2024 to August 2025, were included in this study. All subjects were matched for gestational age (6-8 weeks) to eliminate confounding effects on ultrasound and hormonal measurements. Transvaginal ultrasound parameters [the thickness of the muscular layer at the scar site (T) and the average diameter of the gestational sac/mass (D)], along with serum estradiol (E2) and β-human chorionic gonadotropin (β-hCG) levels, were synchronously collected. The results showed that T, D, E2 and β-hCG in the CSP group were all lower than those in the control group (P<0.05), and the blood flow grades were mainly II-III, accounting for 74.49% of cases. There was no correlation between E2 and β-hCG in the CSP group, while in the control group, the level of E2 was positively correlated with the level of β-hCG. The area under the curve (AUC) of the combined index of T + D + E2 + β-hCG for diagnosing CSP was 0.892, with a sensitivity of 88.78% and a specificity of 77.17%, which was superior to the single index (P<0.05). In addition, we also found that E2 and T were negatively correlated with intraoperative blood loss (P<0.05). These results indicate that estrogen combined with ultrasound parameters can effectively diagnose the occurrence of CSP, providing reference opinions for clinical practice.