Characteristic images of deeply infiltrating rectosigmoid endometriosis on transvaginal and transrectal ultrasonography

BACKGROUND: To evaluate the usefulness of transvaginal and transrectal ultrasonography for diagnosis and management of deeply infiltrating rectosigmoid endometriosis. METHODS: A series of six patients (aged 32-39 years) with rectosigmoid endometriosis underwent transvaginal and transrectal ultrasonography. In three patients undergoing surgical resection of the intestine, the ultrasonographic findings were compared with macroscopic and microscopic findings. In one patient, sequential observations of the lesion using ultrasonography were conducted before and after medical treatment and following childbirth. RESULTS: In all cases, the lesion was detected as a hypoechoic irregular-shaped area surrounded by a hyperechoic rim located posterior to the uterus, with size ranging from 18 x 17 to 29 x 28 mm in diameter. The comparison of the ultrasonographical findings with histology revealed that the hypoechoic irregular-shaped area corresponded to a layer of hypertrophic muscularis propria of the lesion, while the hyperechoic rim represented the layer including the mucosa, submucosa and serosa. In one patient, the lesion decreased in size and lost its central hypoechoic area after childbirth in association with pain relief. CONCLUSIONS: Transvaginal and transrectal ultrasonography provides characteristic appearances for rectosigmoid endometriosis that correlate well with its histological findings. The procedures would be useful in the management of rectosigmoid endometriosis.