Utility of a side-viewing upper echoendoscope for endoscopic ultrasonography of malignant and benign conditions of the sigmoid colon and the rectum

Purpose: Majority of data on colonic EUS is limited to malignant lesions in the rectum and diseases of the anal sphincter. The side viewing upper echoendoscope has mostly been applied for staging rectal cancer as further advancement into the colon is difficult due to side viewing optics. A front viewing echocolonoscope is available but has not been widely used due to limited indications and the expense of buying another instrument. The purpose of this study was to evaluate the utility of a side viewing upper echoendoscope (GFUM20, Olympus) for EUS of malignant and benign lesions of the sigmoid colon and the rectum. Methods: Thirty two EUS exams were performed for a variety of indications in the rectum and the sigmoid colon. The patients were prepared for the exam in a manner similar to the performance of flexible sigmoidoscopy (e.g. two laxative enemas 1-2 hours prior to the procedure). Flexible sigmoidoscopy was performed in all cases prior to performing EUS. Surgical path data was reviewed in all cases where the patient went to surgery and pathology results were accessible. Results: Twenty six exams were done for staging of recto-sigmoid carcinoma, follow-up after chemotherapy and/or radiation, or to look for recurrence after resection of colorectal cancer. Surgical pathology results were available in 20 patients. The accuracy of EUS for T-staging was 85% and for N-staging was 80%. Six EUS exams were for benign causes including evaluation for the presence of a peri-rectal abscess in 2 (no abscess found), to rule out rectal varices in 1 (EUS confirmed rectal varices), and evaluation of submucosal compression of rectosigmoid colon in 3 (2 had leiomyomas by EUS and 1 had a lipoma). One patient subsequent to EUS imaging also underwent a linear EUS guided FNA of a submucosal mass in the rectum with the aspirate consistent with a myogenic tumor which was confirmed by surgical resection. The distance of benign and malignant lesions ranged from 1 cm to 40 cm from the anal verge. Conclusions: The side viewing upper echoendoscope is a versatile instrument that can be applied for malignant & benign indications not only in the rectum but the sigmoid colon as well, up to 40cm from the anal verge.