Transvaginal ultrasonography with water-contrast in the rectum in the diagnosis of bowel endometriosis

AIM: The rectosigmoid is the most frequent location of intestinal endometriosis. Although several techniques have been proposed for the diagnosis of intestinal endometriosis, no gold standard is currently available. In this review, we describe in details a new technique for the diagnosis of rectosigmoid endometriosis: rectal water-contrast transvaginal ultrasonography. METHODS: During transvaginal ultrasonography, an assistant inserts a 6-mm flexible catheter through the anal os into the rectal lumen; the insertion of this catheter is evaluated under ultrasonographic control. Water contrast is instilled slowly in the rectum to permit intestinal distension. The colonic wall evaluation is obtained by positioning the transvaginal probe against a length of the sigmoid colon to obtain either axial or longitudinal images. The injection of the saline solution facilitates the identification of recto-sigmoid endometriotic nodules which appear as rounded or triangular hypoechoic masses, located anterior or lateral to the bowel. RESULTS: This technique has high sensitivity and specificity in the diagnosis of rectal infiltration in women with rectovaginal endometriosis. The distance between the nodules and the mucosal layer permits to estimate the depth of infiltration of these endometriotic lesions within the intestinal wall. Rectal distensibility can be estimated. The procedure is well tolerated by the patients. CONCLUSION: Water distention of the rectum facilitates the identification of intestinal endometriosis during transvaginal ultrasonography.