Morphological Features in Transabdominal and Transvaginal Ultrasonography for the Assessment of Adnexal Masses: A Cross-Sectional Diagnostic Accuracy Study

Background: Accurate preoperative characterization of adnexal masses is critical for appropriate clinical management. Transabdominal (TAS) and transvaginal (TVS) ultrasonography remain the first-line imaging modalities for morphological assessment of adnexal masses. Objectives: To describe and compare the morphological features of adnexal masses using TAS and or TVS to evaluate the diagnostic performance of the International Ovarian Tumor Analysis (IOTA) Simple Rules, and to analyze feature patterns across histopathological subtypes. Methods: This cross-sectional study included 47 women with adnexal masses scheduled for surgery. All patients underwent TAS and or TVS with color doppler (based on IOTA Simple Rules). Morphological features were classified according to the IOTA Simple Rules. Histopathological diagnosis is considered the gold standard. Diagnostic accuracy of IOTA (Simple Rules) were calculated and compared with existing literature. Results: The mean age of the participants was 35.6 ± 14.3 years. Histopathological analysis confirmed 24 (51.1%) benign masses, 22 (46.8%) malignant masses, and 1 (2.1%) borderline tumor. Among IOTA morphological features, the most significant benign indicator was the absence of blood flow (Color Score 1, 44.7%), whereas the most prevalent malignant indicator was very strong blood flow (Color Score 4, 40.4%). IOTA Simple Rules demonstrated a sensitivity of 91.3%, specificity of 87.5%, PPV of 87.5%, and NPV of 91.3%, with an overall diagnostic accuracy of 89.3%. Analysis by tumor subtype revealed that epithelial carcinomas predominantly exhibited high vascularity and irregular solid components, while benign lesions typically presented with unilocular or smooth multilocular morphology. Conclusion: IOTA Simple Rules provide high diagnostic accuracy in differentiating adnexal masses. While TVS is superior for characterizing internal morphological details and papillary projections, TAS remains an essential adjunct for evaluating large masses (>10 cm) and identifying extra-pelvic spread such as ascites. The integration of standardized IOTA morphological features into routine TAS and TVS examinations significantly improves preoperative risk stratification.