With regard to what tests to perform, most authorities will recommend a total colonic examination, meaning either a double contrast barium enema or a colonoscopy. A flexible sigmoidoscopy is a test in which an endoscope or a tube with a video camera on the tip is placed into the rectum and the lining of the bowel can be evaluated for polyps and cancers. It is performed by primary care practitioners, gastroenterologists, surgeons, and occasionally by nurse assistants, nurse practitioners, and physicians assistants. The primary risk of flexible sigmoidoscopy is perforation of the bowel. However, that risk is extremely low and is approximately 1 in 10,000 procedures.
Flexible sigmoidoscopy is a very accurate test for the area of the bowel that it does evaluate.
Whether one needs a second test, depends on whether one is concerned about those abnormalities that could be above the visualization of the sigmoidoscope. A double contrast barium enema is performed by a radiologist. It is a test in which a small flexible tube is inserted just in the lower portion of the rectum and then barium is administered into the colon and by turning the patient, it is moved throughout the colon. At the point in which the barium fills the entire colon, then air is put into the colon through the same tube to open up the colon and allow the X-ray to pass through and visualize small polyps and cancers that are coated with the barium . The risks of the double contrast barium enema are predominantly perforation, which occurs in 1 in 25,000 procedures.