E2606. Everything You Need to Know About Rectal Endometriosis: Diagnosis, Standard Reporting and Management
  1. Garvit Khatri; University of Washington
  2. Deepashri Basavalingu; University of Washington
  3. Manjiri Dighe; University of Washington
Endometriosis is a common chronic gynecological disorder presenting with cyclical pain and infertility in premenopausal females. In some patient’s endometrial lesions can be advanced and infiltrate deep into the peritoneum (deep infiltrating endometriosis (DIE)) and pelvic organs, and cases can be challenging for management. Posterior compartment endometriosis, in particular involvement of the recto-sigmoid can be challenging for surgeons, and presurgical detection and proper characterization of involvement on imaging is prudent. Ultrasound and MR are the main modalities to evaluate pelvic endometriosis. Imaging evaluation requires identifying the number, location and size of the lesions, as well as the degree of depth and circumferential involvement of the rectum. In this exhibit we plan to include detail imaging of such cases and mentioned about the rectal endometriosis reporting guidelines set by Society of Abdominal Radiology (SAR).

Educational Goals / Teaching Points
To present the Ultrasound and MR features of rectal endometriosis. To understand the SAR reporting guidelines. To understand the Ultrasound sliding sign

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Ultrasound: Transvaginal ultrasound is usually initial modality for evaluation of patients with pelvic pathologies including suspected endometriosis, Koga et al defined the diagnostic criteria at ultrasound for bowel endometriosis as hypoechoic, irregular-shaped lesions surrounded by a hyperechoic rim usually within the muscularis propria layer. Sometimes, the normal muscularis propria of the rectum can be replaced by hypoechoic retractile endometriotic deposit, giving an irregular shape structure resembling a ‘Moose Antler’ or ‘Indian Headdress’ sign. A negative uterine sliding sign, described as immobility of rectum relative to uterus or the posterior vaginal fornix suggests Pouch of Douglas involvement by endometriosis, which increases likelihood of posterior compartment DIE and rectal involvement by almost 3 times. MR: Scanning: Essential sequences on MRI include axial T1 weighted fat saturated, axial oblique T2 weighted (perpendicular to cervix), coronal T2 weighted and sagittal T2 weighted images. Antispasmodics are recommended to decrease artifacts from bowel peristalsis. Endometriotic lesions usually have signal characteristic like that of smooth muscle, including low signal intensity on T2 weighted images, intermediate signal intensity on T1 weighted images, and minimal enhancement after intravenous contrast administration. Mushroom cap sign: The endometrial deposit grows into the layers of the bowel lumen with the mucosa and submucosa appearing bright at the growing edge of the nodule on T2 sequences,, resembling a cap of a mushroom. MR can predict depth and circumference of bowel wall involvement

Successful management of endometriosis depends on complete removal of all lesions. Surgical management of rectal endometriosis may be complicated, and preoperative knowledge and proper description of these lesions, helps guide surgeons to decide the right surgical approach.