Poor sensitivity of transvaginal ultrasound markers in diagnosis of superficial endometriosis of the uterosacral ligaments

Introduction:This study aims to evaluate the use of transvaginal ultrasound in predicting superficial endometriosis near the uterosacral ligaments, in women with symptoms of endometriosis.Methods:This was a prospective observational pilot study in which women with symptoms of endometriosis underwent detailed pre-operative transvaginal ultrasound to assess the uterosacral ligament area for thickening (‘white line sign’), tenderness and small hypoechoic nodules. Women with deep infiltrating endometriosis were excluded. The test characteristics of transvaginal ultrasound were reported using histologically or visually proven endometriosis near the ipsilateral uterosacral ligament as a reference standard.Results:In 81 patients who underwent pre-operative transvaginal ultrasound and laparoscopy, no marker had appropriate test characteristics for a diagnostic or screening test for endometriosis near the ipsilateral uterosacral ligament when used alone. The presence of a small hypoechoic nodule on the white line had the highest specificity of the three markers, at 82% (95% confidence interval 66%–92%). Quantitative measurement of the white line also achieved a high specificity of ≥96% using a cut-off of 5.8 and 6.1 mm, on the left and right sides, respectively.Conclusion:Transvaginal ultrasound of the uterosacral ligament area using the three proposed markers is not a clinically useful screening test for superficial endometriosis near the uterosacral ligaments. A grossly thickened white line (≥5.8 mm) and/or the presence of small hypoechoic nodules are highly specific findings for superficial endometriosis near the uterosacral ligaments and may prompt surgical management.