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Alternatives

Other tests exist that can help your doctor to detect diseases of the colon. Sometimes these tests can be done instead of a colonoscopy, but at other times they are performed in addition to a colonoscopy because each test can provide different types of information.

• With similar preparation, a special x-ray examination of the entire colon, a barium enema, can be used instead of or in addition to colonoscopy. For this test, a liquid called barium is inserted into the colon using a small tube through the anus. X-rays are then taken of the abdomen with the barium inside. This liquid is seen on the x-ray and is used to outline the irregularities of the bowel wall.
  
  
• Another test called a sigmoidoscopy can be performed. This test is very similar to a colonoscopy but requires less preparation. The instrument used, a sigmoidoscope, is 2 ft long and allows visualization of the anal canal, rectum, and the part of the colon closest to the rectum known as the sigmoid colon. Although this test is important, it does not allow detection of abnormalities in other areas of the colon because the sigmoidoscope is much shorter than the colonoscope.
  
  
• CT scans are often used to investigate abnormalities of the abdomen. Gastrografin is a liquid similar to barium, which allows the bowel to be seen better during a CT scan. This liquid, also called oral contrast, is swallowed and then allowed to pass from the stomach, through the small intestine (the ileum) and then through the large intestine (the colon) before the CT scan is performed. In this way, a CT scan can be helpful to investigate abdominal and bowel problems.
  
  
• Your doctor will decide which of these tests is most appropriate for you.