Instead of a colonoscopy, a patient may have a flexible sigmoidoscopy. Similar to a colonoscopy, this procedure uses a shorter tube to investigate the lower parts of the colon (sigmoid colon and descending colon). Sigmoidoscopies produce less discomfort than colonoscopies, but they check only part of the colon rather than the entire colon. Patients should weigh the relative advantages and disadvantages of each type of procedure and consult with a physician about which test is best for them.

There are other tests that are also used to screen the rectum and colon for abnormalities. These include:

• Stool blood tests. The primary version of this test is known as a fecal occult blood test (FOBT). The patient is provided a kit that allows them to collect a stool sample at home. The sample is then analyzed for traces of hidden blood. If blood is found, further testing may be required. A newer stool blood test called a fecal immunochemical test (FIT) may be easier for some to use and may produce fewer false positives.
  
  
• Barium enema. A chalky substance called barium is inserted to fill and distend the colon. Air is then pumped in to expand the colon, and x-rays are taken. This procedure is not as accurate as a colonoscopy, and is generally used only when a patient cannot undergo a colonoscopy or does not have access to the procedure.

A newer version of the colonoscopy called a virtual colonoscopy creates detailed two- and three-dimensional x-ray images of the colon without using a conventional colonoscope. It can be performed using a computed axial tomography (CAT) scan, which uses special x-ray equipment to obtain cross-sectional pictures of the body; or magnetic resonance imaging (MRI), which uses a large magnet, radio waves and a computer to produce images rather than x-rays.