OC16.02: Ultrasound diagnosis of uterosacral ligaments' endometriosis: description of a new sign

Pelvic endometriosis is suspected by clinical examination but only confirmed by histology. Before surgery, transvaginal ultrasonography and magnetic resonance imaging are useful for lesions mapping. Uterosacral ligaments are affected in 69% of patients with deep infiltrating endometriosis. We propose a new ultrasound sign to detect the infiltration of uterosacral ligaments. In this prospective observational study, patients were explored by the same sonographer, for pelvic chronic pain. Preoperative ultrasound images digitally archived were examined without knowing operative results, looking for a new sign of uterosacral ligament's endometriosis. This sign corresponds to a distortion of the natural curvature of the endocervix-endometrial junction on a strict sagittal uterine axis, resulting from uterine posterior adhesions caused by endometriosis. The sign was not present if there is a harmonious curvature of the junction without interruption. Presence or absence of the sign was compared to the presence of a deep infiltrating endometriosis involving uterosacral ligaments confirmed by surgery and histology. 52 patients were included during the study period. We identified the sign for 37 of 52 patients by analysing ultrasound images. At surgery, uterosacral ligaments' endometriosis was found for 38 of 52 patients. The sensitivity of this new sign in our population was 81% (95% CI: 65-92), and the specificity 57% (95% CI: 29-82), with a C-index of 0.69 (95% CI : 0.54-0.84). We propose a new ultrasound sign of uterosacral ligaments' endometriosis, useful for preoperative mapping. Nonetheless, we studied the new sign on pictures while we should appreciate this sign during the examination, taking advantage of dynamic character of ultrasound exam.