Transvaginal Ultrasound for Endometriosis: Learning From a Decade of Diagnostic Challenges Through a Retrospective Observational Cohort Study

BACKGROUND: Endometriosis is a chronic, inflammatory condition associated with pelvic pain, subfertility, and reduced quality of life. Advances in enhanced transvaginal ultrasound (eTVUS), including systematic compartment-based scanning protocols and improved operator training, have increased diagnostic accuracy, particularly for deep endometriosis. AIMS: To evaluate and critically reflect on the diagnostic performance of eTVUS during its implementation prior to the adoption of standardised scanning protocols. Using the #ENZIAN classification system, the diagnostic performance of eTVUS was assessed by comparing ultrasound findings with laparoscopic visualisation as the reference standard. METHODS: A retrospective observational study of patients with suspected endometriosis who underwent preoperative eTVUS and subsequent laparoscopy between January 2015 and January 2024 at a single tertiary hospital. Ultrasound and surgical findings were mapped to #ENZIAN compartments and grades. Agreement and diagnostic metrics were calculated using laparoscopy as the reference standard. RESULTS: Among 221 patients with paired ultrasound and laparoscopy, adnexal endometriomas were detected with a sensitivity of 81.4% and specificity of 84.1%. Tubo-ovarian complex disease demonstrated a sensitivity of 72.9% and specificity of 68.8%. Sensitivity for deep endometriosis was lower, with specificity for detection depending on anatomical location varying from 83%-95%. Bladder involvement had a PPV of 83.3% and NPV of 94.8%; ureteric disease had a PPV of 0% and NPV of ~100%. Peritoneal disease was rarely identified. CONCLUSION: eTVUS demonstrated high diagnostic accuracy for ovarian endometriomas, moderate performance for bowel involvement, and low sensitivity for peritoneal disease.