MRI and "tenderness guided" transvaginal ultrasonography in the diagnosis of recto-sigmoid endometriosis

PURPOSE: To compare the diagnostic accuracy of MRI and "tenderness-guided" transvaginal ultrasonography (tg-TVUS) in the identification of recto-sigmoid endometriosis. MATERIALS AND METHODS: Institutional Review Board approval for this study was obtained, and written informed consent was given by all patients. This study is compliant with the STARD (Standards for Reporting of Diagnostic Accuracy) method. Fifty-nine patients (mean age, 33 years; range, 21-44 years) with clinical suspicion of deep pelvic endometriosis were prospectively enrolled. They underwent tg-TVUS and MRI before surgery. The characteristics of the MRI signal were analyzed. Mapping of recto-sigmoid endometriosis was performed and tg-TVUS and MR imaging results were compared with surgical and pathological findings. Sensitivity, specificity, and the positive and negative likelihood ratio (LR+ and LR-) were calculated. Inter-technique concordance was assessed using the Cohen statistic, and receiver operating characteristic (ROC) curves were obtained. Logistic regression analysis was performed. RESULTS: The prevalence of recto-sigmoid endometriosis was 51%. The specificity, sensitivity, and LR+ and LR- were 90%, 73%, 7.089 and 0.297, respectively, for MRI and 86%, 73%, 5.317 and 0.309, respectively, for tg-TVUS. The presence of a high T1 signal spot was an excellent specific finding (100%) but was associated with a low sensitivity (30%). Inter-technique concordance using the Cohen statistic indicated a kappa value of 0.658 (± 0.098 SD). According to the logistic regression equation obtained, the use of both tg-TVUS and MRI allows optimal diagnostic performance. CONCLUSION: MRI and tg-TVUS show similar results in the identification of recto-sigmoid endometriosis. The Cohen kappa value suggests that these methods may have complementary roles in the identification of recto-sigmoid endometriosis, depending on the site affected.