Disadvantages include that most patients with microscopic blood in the stool do not have cancer or other serious disease, so the test leads to a lot of unnecessary additional tests and x-rays. In this test, a flexible video scope examines the lower colon. Disadvantages are that it does not visualize the entire colon, and there is a very slight risk of injury as the scope is inserted. The American Cancer Society recommends this test every three to five years for everyone over age 50. This is a series of x-rays of the colon done at the hospital after a contrast agent is inserted by enema into the colon.
Advantages are that it offers excellent visualization of the entire colon.
Disadvantages are that it requires extensive preparation, is somewhat uncomfortable, and may be limited if the bowel is not completely cleaned out. This test can be used for screening but more often is reserved to examine patients who have had a positive occult stool blood test, or other suspicious signs or symptoms. This test uses a scope that is longer than that used in the flexible sigmoidoscopy, thus can examine the entire colon. It is generally performed as an outpatient surgical procedure as it requires intravenous sedation and monitoring. Advantage is that it examines more of the colon than the sigmoidoscopy and disadvantages include that intravenous sedation slightly increases risk, it requires extensive bowel cleansing and it is significantly more expensive, though covered under most insurance plans.