Integrated Risk Stratification and Stepwise Diagnostic Algorithm for Clinically Significant Caesarean Scar Defects in Women with Reproductive Dysfunction

Background: A post-caesarean uterine niche may be incidental or associated with postmenstrual spotting, pelvic symptoms and reproductive difficulties. Distinguishing structural abnormalities from clinically important lesions remains challenging when imaging is interpreted in isolation. Objective: To examine clinical, obstetric, ultrasonographic and Doppler variables associated with clinically significant caesarean scar defects and to describe the apparent discrimination of a combined risk score and sequential imaging strategy in women with and without reproductive dysfunction. Methods: This two-centre observational comparative study included 150 women aged 18–45 years with a caesarean delivery at least six months earlier: 100 with reproductive dysfunction and 50 without such dysfunction or severe scar-related symptoms (2021–2025). All underwent clinical assessment, transvaginal ultrasonography and Doppler evaluation; MRI was used selectively in 92 women and hysteroscopy in 86. An integrated clinical/imaging assessment classified defect significance. Associations were reported using logistic regression and discrimination using receiver operating characteristic analysis. Because the reference classification included imaging and symptoms, diagnostic accuracy estimates are potentially affected by incorporation and verification biases. Results: Clinically significant defects were reported in 72/100 women (72.0%) with reproductive dysfunction and 9/50 controls (18.0%). The strongest reported adjusted associations were residual myometrial thickness ≤2.5 mm (odds ratio [OR] 6.37, 95% confidence interval [CI] 2.63–15.43) and a residual-to-adjacent myometrium ratio ≤50% (OR 5.21, 95% CI 2.13–12.73). The reported combined-model area under the ROC curve was 0.94 (95% CI 0.90–0.97); apparent sensitivity and specificity were 90.1% and 89.9%. The proposed 13-point score defined low- (0–3), intermediate- (4–7), and high-risk (8–13) groups with reported defect frequencies of 14.6%, 52.7%, and 95.7%, respectively. Ultrasound plus Doppler showed reported sensitivity of 96.3% and specificity of 88.4%. Conclusion: Combining symptoms, obstetric history and scar morphometry may aid clinical triage after caesarean delivery. The risk score and apparent diagnostic performance require independent evaluation using an explicitly defined reference standard before clinical implementation.