Diagnostic accuracy of transvaginal ultrasound for adenomyosis using consensus-based direct and indirect sonographic signs: prospective cohort study.

OBJECTIVE: To evaluate the diagnostic performance of transvaginal ultrasound (TVS) for adenomyosis using consensus-based direct and indirect ultrasound signs, with histopathology as the reference standard. METHODS: This prospective diagnostic accuracy study included women undergoing TVS examination at a tertiary referral center (Hospital San Juan de Dios, Santiago, Chile) between 1 December 2022 and 1 December 2023. Women aged ≥ 18 years who underwent hysterectomy within 6 months after TVS examination were enrolled consecutively. Cases with malignant histopathological findings were excluded. Ultrasound signs of adenomyosis were assessed according to the revised Morphological Uterus Sonographic Assessment consensus. Histopathology served as the reference standard. Diagnostic performance measures for individual ultrasound features and multivariable models were calculated. RESULTS: Among 2967 women evaluated using TVS, 345 (11.6%) underwent hysterectomy within 6 weeks and constituted the study cohort. Histopathology confirmed adenomyosis in 155 (44.9%) women. Individual ultrasound features showed high specificity but limited sensitivity. Among direct signs, echogenic subendometrial lines showed the best overall balance (sensitivity, 53.5% (95% CI, 45.4-61.6%); specificity, 94.7% (95% CI, 90.5-97.4%)). Individual indirect signs showed specificity > 97% but low sensitivity. A model combining direct ultrasound signs showed high specificity (93.7% (95% CI, 89.2-96.7%)) but limited sensitivity (60.0% (95% CI, 51.8-67.8%)); overall diagnostic accuracy was 78.6% (95% CI, 73.8-82.8%). The addition of indirect ultrasound signs into the model did not provide meaningful incremental benefit. CONCLUSIONS: Our findings highlight the importance of distinguishing between direct and indirect ultrasound features, with direct signs providing the most consistent diagnostic value, while indirect signs should be interpreted as supportive rather than definitive. © 2026 International Society of Ultrasound in Obstetrics and Gynecology.