Transvaginal ultrasound for deep endometriosis: Prospective validation of SRU criteria and diagnostic value of indirect signs

BACKGROUND: The SRU consensus on pelvic ultrasound proposed standardized augmented ultrasound, but its validity and indirect signs' role require validation. This study will explore the application value of this consensus in deep endometriosis. METHOD: This prospective study enrolled patients with clinically suspected endometriosis at Qingdao University Affiliated Hospital from May 2024 to April 2025. TVUS findings were compared with surgical findings. The diagnostic performance of TVUS for endometriosis was calculated, and multivariable logistic regression was applied to analyze associations between indirect sonographic signs and lesion locations. RESULTS: Included were 288 patients with clinical suspicion of DE. For DE detection, TVUS showed an overall accuracy of 84.4% (sensitivity 87.4%, specificity 76.8%). Fixed uterine retroflexion was significantly associated with bowel (OR 2.07, 95% CI 1.16-3.71), RVS (OR 2.83, 95% CI 1.34-6.32), and uterine serosal involvement (OR 2.38, 95% CI 1.19-4.88). Bowel tethering predicted bowel (OR 6.45, 95% CI 3.69-11.53), RVS (OR 4.53, 95% CI 2.24-9.62), uterine serosal (OR 2.15, 95% CI 1.12-4.18), and vaginal lesions (OR 3.83, 95% CI 1.85-8.25). Ipsilateral ovarian fixation or abnormal position was indicative of ipsilateral ovarian endometriosis (right: OR 16.9, 95% CI 9.15-32.96; left: OR 14.54, 95% CI 8.02-27.63) and USL involvement (right: OR 4.38, 95% CI 2.40-8.29, left: OR 2.23, 95%CI 1.3-3.91). CONCLUSION: SRU-based ultrasound demonstrates high diagnostic accuracy for DE. Indirect signs effectively localize endometriotic lesions, enhancing surgical planning.