Colorectal EUS

Applications for endoscopic ultrasound (EUS) in the colon and rectum have continued to expand since introduced in the early 1980s. The use of rigid probes is limited to evaluation of the distal rectum and anal canal. EUS endoscopes are flexible and may be used in the rectum and accessible proximal colon. Bowel preparation for colonic examination by endosonography is variable depending on the area to be imaged. Laxative enemas similar to the preparation for flexible sigmoidoscopy may be sufficient for anorectal and sigmoid lesions. EUS is primarily used for local staging of rectal cancer. Accurate staging of rectal cancer is important in determining management including both surgical approaches, need for preoperative chemoradiation and predicting or identifying recurrence. The application of EUS-guided fine-needle aspiration may be used as an adjunct to accurate lymph node assessment during EUS, and it has been applied in patients with rectal cancer.