VP62.21: Quantitative shear wave ultrasound elastography in patients with deep endometriosis

Deep endometriosis is a fibrotic condition in which endometrial stroma and epithelium can be identified. Shear wave elastography (SWE) is a modern method of obtaining quantitative tissue elasticity data during ultrasound examinations. Our primary aim was to evaluate deep endometriotic nodules quantitatively using SWE. We conducted a prospective observational study at a high volume tertiary referral centre at a university hospital from December 2019-March 2020. 124 deep endometriotic nodules were measured in 84 consecutive patients with a transvaginal transducer. Sonography was performed according to the IDEA protocol. Nodules location and size were ranked based on the Enzian classification. We determined with SWE both tissue elasticity (kPa) and shear wave velocity (m/s). For each nodule, control values were obtained at the same depth from the transducer from the identical nonaffected organ and peritoneal surface sections. Laparoscopic surgery and histological examination as gold standard were performed for all patients. Median values of the tissue elasticity of the endometriotic nodules was nine times (79.35 vs. 8.82 kPa, p < 0,001) and the shear wave velocity three times (5.34 vs. 1.76 m/s, p < 0,001) that of the control tissues. In the posterior compartment there is no significant difference between the elasticity and the shear wave velocity of nodules in the rectovaginal septum (18/124), uterosacral ligament (39/124) or in the rectum (53/124). In the bladder (14/124), the nodules are softer compared to the nodules in the posterior compartment. There is no correlation between the size of the nodule (r:0.367), or its distance from the transducer (r:0.139) and its elasticity. Age is directly proportional (r: 0.951) to the elasticity of the nodules in all location. SWE appears to be an objective, reliable method in verifying deep endometriosis found by ultrasonography. Rectovaginal deep endometriosis in the posterior compartment seems to be harder than bladder nodules.