Endometrial Thickness as a Prognostic Marker in Premenopausal Abnormal Uterine Bleeding: Diagnostic Accuracy and Kaplan–Meier Survival Insights

<ns3:p>Background Abnormal uterine bleeding (AUB) in premenopausal women is frequent, yet distinguishing benign from malignant causes remains clinically challenging. Endometrial thickness (ET) measured by transvaginal ultrasound (TVUS) is well established in postmenopausal bleeding but less validated in premenopausal women due to cyclical variations. This study aimed to assess the diagnostic accuracy and prognostic value of ET, supplemented by Kaplan–Meier survival analysis, in predicting endometrial malignancy among premenopausal women with AUB. Methods We conducted a retrospective observational study including premenopausal women presenting with AUB at Charles Nicolle Hospital, Tunis, Tunisia (2016–2024). All underwent TVUS followed by endometrial sampling (hysteroscopy or curettage) and definitive histological confirmation on hysterectomy specimens. Sonographic features were described using International Endometrial Tumor Analysis (IETA) criteria. Diagnostic performance of ET was evaluated using receiver operating characteristic (ROC) curve analysis. Kaplan-Meir survival analysis was applied to time-to-consultation and time-to-diagnosis, not survival outcomes. Results ROC analysis identified ET as the strongest predictor of endometrial malignancy (AUC = 0.842, p &lt; 0.001). An optimal cutoff of &gt;9 mm achieved 69.2% sensitivity, 87.1% specificity, and a negative predictive value of 97.7%, effectively ruling out malignancy in patients with ET ≤9 mm. Although the positive predictive value was modest (26.5%), ET reliably stratified risk for further invasive evaluation. Kaplan–Meier analysis demonstrated that ET &gt;9 mm was associated with earlier consultation (mean 27.7 vs. 70.3 months, p &lt; 0.0001) and shorter time-to-diagnosis (median 12 months vs. not reached, p &lt; 0.0001), reflecting a more aggressive clinical course. Conclusions ET &gt;9 mm is a robust, non-invasive potential prognostic marker in premenopausal AUB, identifying high-risk women requiring urgent evaluation while safely excluding malignancy in low-risk patients.</ns3:p>