Usefulness of transvaginal strain elastography in the diagnosis of deep infiltrating endometriosis in the posterior compartment

To perform a preliminary investigation into the use of strain elastography in order to determine the effectiveness of this method for the evaluation of deep infiltrating endometriosis (DIE) nodules in the posterior compartment. We used the IDEA (International Deep Endometriosis Analysis group) sonography overview protocol for patients with suspected endometriosis. Over a period of 16 months 305 consecutive patients were examined. The degree of strain was visualized using the color codes placed on the B-mode image. In the posterior compartment at the suspected endometriotic nodules and their adjacent tissues covered with peritoneum, the tissue displacement rates were computed. Differences in the tissue deformity were then compared to non-affected organs and peritoneal sections. Laparoscopic surgery and histological examination were performed for all patients. In the rectovaginal space using strain elastography, deep infiltrating nodules presented a typical blue (hard) appearance with a clearly defined outer border. The method showed 98% rectal and 93% of the rectosigmoidal nodules. Sacrouterine ligament nodules were detected in 97%. Strain ratios in the nodules varied from 0.059% to 0.212%. A difference in the tissue deformity values of more than twice that of control area was significant for the isolation of endometriosis nodule (P: 0,001). In 62% of DIE nodules the central area of the nodule was softer (green) then the marginal zone. Elastography of the rectovaginal space may be an objective method for assessment of deep infiltrating endometriosis in the posterior compartment. Using the data earned by the elastography about the severity of the disease may help to guide the surgeon preparing for surgical intervention.