Colonoscopy No abnormalities of structure or mucosal surface are observed in the colon or terminal ileum. Using intravenous sedation, the endoscope is inserted into the rectum and passed through the sigmoid, descending, transverse, and ascending colon, cecum, distal ileum. The lumen is visualized and tissue specimens may be collected for cytology examination. To identify and biopsy abnormal tissue in the colon and terminal ileum To investigate the cause of Chronic Diarrhea, locate the source of GI bleeding To evaluate the colon for recurrent polyps or malignant growth Diverticulitis Ulcerative Colitis Polyps Carcinoma Colitis "Gay bowel syndrome" Crohn's Disease Massive bleeding Inflammatory Bowel Disease Stricture Peritonitis Bowel perforation Recent acute cardiopulmonary disease Recent pelvic or colon surgery Large aortic or iliac aneurysm Pregnancy, second or third trimester Uncooperative behavior Retained barium Failure to maintain pretest dietary restrictions