OC16.05: Computed tomographic colonography versus transvaginal ultrasonography in the diagnosis of rectosigmoid endometriosis

To compare the accuracy of computed tomographic colonography (CTC) and transvaginal ultrasonography (TVS) in the diagnosis of rectosigmoid endometriosis. This prospective study was performed between October 2013 and March 2015 and included women with strong suspicion of intestinal endometriosis based on symptoms and clinical examination. Patients were excluded if they had previous colorectal surgery, contraindications to bowel preparation or CTC. The exams were performed independently and blindly. CTC and TVS findings were compared with surgical and pathologic results. Efficacy parameters were calculated with 95% confidence intervals. Out of 73 women enrolled in the study, 57 underwent surgery and were included in the final analysis. 33 women (57.9%) had recto-sigmoid endometriosis at surgery. 15 nodules were located on the sigmoid, 12 nodules were located on the rectum and 6 nodules were located on the rectosigmoid. The sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios and accuracy of CTC and TVS in diagnosing rectosigmoid endometriosis were respectively 93.9% (95% C.I., 74.7%–99.1%), 91.7% (73.0%–98.7%), 11.27 (2.98–42.61), 0.07 (0.02–0.25), 93.9% (79.7%–99.1%), 91.7% (73.0%–98.7%), 93.0% and 90.6% (75.0%–97.9%), 96.0% (79.6%–99.3%), 22.66 (3.31–100.00), 0.10 (0.03–0.29), 96.7% (82.7%–99.4%), 88.9% (70.8%–97.5%), 93.0%. There was no significant difference in the accuracy of the two techniques in the diagnosis of rectosigmoid endometriosis (p = 0.683; McNemar's test). CTC was more accurate than TVS in estimating the distance between the nodule and the anus (p = <0.001). Both CTC (rho = 0.737, p = 0.01) and TVS (rho = 0.779, p = 0.01) were accurate in estimating the largest diameter of the nodule. CTC and TVS are equally effective in diagnosing recto-sigmoid endometriosis and in estimating the size of the nodule. CTC is more accurate than TVS in estimating the distance between the nodule and the anus.