Deep infiltrating endometriosis of the bowel wall: the comet sign

The purpose of this study was to evaluate the appearance of deep infiltrating endometriosis of the bowel wall in the cul-de-sac and determine the characteristic appearance of these lesions. We searched our database between January 1, 2011, and December 31, 2013, for all patients who had sonographic findings of suspected deep infiltrating endometriosis of the bowel with obliteration of the cul-de-sac. The medical record of each patient was examined retrospectively for evidence of surgical confirmation of disease. The sonographic appearance, shape, and size of the bowel wall lesions were evaluated to develop criteria for deep infiltrating endometriosis of the rectosigmoid and cul-de-sac. The search of our database revealed 35 patients with sonographic findings of pelvic bowel wall endometriosis associated with obliteration of the cul-de-sac. Ten of these patients had surgical confirmation of bowel wall endometriosis after the scan, and another 4 patients had surgical evidence of endometriosis from prior surgery. All of the patients who underwent surgery subsequent to sonography had confirmation of their bowel wall infiltrative endometriosis. Sonographically, the bowel lesions were solid, focal, and tubular with slightly irregular margins and in most cases a thinner section or a "tail" at one end, resembling a comet. This study confirms that bowel wall implants have a very characteristic appearance, and extending the transvaginal examination to include an evaluation of the rectosigmoid seeking these bowel lesions is valuable, especially in any patient presenting with a history of pelvic pain.