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Virtual colonoscopy

Computed Tomographic Colonography (Virtual Colonoscopy)

Uses X-rays and computers to take 2- or 3-D images of your colon and rectum.

  • Can detect polyps less invasively
  • Clear, liquid diet for 1-3 days prior
  • No sedation, few complications
  • Pricey but less expensive than colonoscopy


  • Quicker than conventional colonoscopy or a barium enema
  • Few complications
  • No sedation, you can return to normal activities immediately
  • Less invasive than conventional colonoscopy
  • Virtual colonoscopy can see inside a colon that is narrowed due to inflammation or the presence of an abnormal growth


  • Air distention of the bowel can be uncomfortable
  • Dietary restrictions for 1-3 days prior/full bowel preparation
  • Less effective in detection of flat polyps and polyps smaller than five millimeters
  • Uses X-ray radiation
  • If polyps or other abnormalities are found, a conventional colonoscopy will be needed to remove or explore more thoroughly
  • Is not covered by Medicare as an initial screening test
  • Newer technology and is not as widely available as conventional colonoscopy

What can I expect for a bill?

Average cost before insurance: $400 – $800

Will my insurance cover it?

The Blue Cross and Blue Shield Technology Evaluation Center has determined that virtual colonoscopy meets criteria to be considered an effective colorectal cancer screening test, and a number of other major health insurers cover the procedure. Policies differ, however, so please check with your health insurance provider to confirm your options.

Medicare does not yet cover virtual colonoscopy. The Centers for Medicare and Medicaid considered it a “new and emerging technology” last time it was evaluated and said it required additional evidence before their decision to cover the costs of the test.

The facts

Computer Tomographic (CT) Colonography, also known as virtual colonoscopy, is used to find polyps, cancer and other diseases of the large intestine through computerized technology.

Here’s what happens: a small tube is placed in the anus and air is pumped into the colon to inflate the bowel. Then a special CT scan is used to image the colon. Recent studies show virtual colonoscopies are very effective in identifying medium to large polyps but may miss small or flat polyps. Low-risk patients who cannot undergo a conventional colonoscopy may favor this less-invasive alternative.

The prep

Since this test is all about the images, it is important the colon and rectum are emptied before the virtual colonoscopy, just like a conventional colonoscopy. This means you will need to follow a clear liquid diet for 1-3 days before the test. See our colonoscopy prep section for more information about getting ready for your virtual colonoscopy.

The procedure

This test is done in a special room with a CT scanner. Don’t be alarmed if you’re asked to drink a contrast solution before the test to help “tag” any remaining stool in the colon or rectum. During the procedure, you’ll be asked to lie on a thin table or bed that is part of the CT scanner and your doctor will insert a small, flexible tube into your anus. When you are ready, air is pumped through this tube into the colon in order to expand it and provide better images. The table then slides into the CT scanner and a series of cross-sectional images of your colon are taken. You will likely have two scans: one while you are lying on your back and the other while you are on your stomach. The total time for the virtual colonoscopy is a mere 10 minutes.

The big 'what if…'

If your doctor detects an abnormal growth, you will need to have a colonoscopy to remove it. Abnormal growths are detected in about 1 out of 5 people who undergo virtual colonoscopy. It’s also possible the CT scan will reveal something outside of the colon which could require additional testing.

After the test

Because there is no sedation involved, recipients can return to normal activities directly following the procedure with no need for assistance. There are usually very few side effects following a virtual colonoscopy. Any feelings of bloat or cramping should go away once the air passes from the body. There is a very small risk that inflating the colon with air could injure or puncture the colon, but this risk is thought to be much less than with a conventional colonoscopy. Like other types of CT scans, this test also exposes you to a small amount of radiation.

How often (if not high risk)

Every 5 years starting at age 45 (though timing has not been closely studied).

CTC Screening for CRC Webinar

This webinar will introduce the colorectal cancer screening modality of CT colonography (also known as virtual colonoscopy). We'll discuss the advantages and disadvantages of screening by this imaging-based method, including the meaning of low dose exposure to medical radiation and the impact of being able to detect unsuspected findings outside of the colon, which is not possible with other screening exams.

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