Computed Tomographic Colonography (Virtual Colonoscopy)

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Computer Tomographic (CT) Colonography, also known as virtual colonoscopies, are 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.
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 one to three days before the test. See your colonoscopy prep section for more information about getting ready for your virtual colonoscopy.
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.
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If your doctor detects an abnormal growth, you will need to have a colonoscopy to remove it. Abnormal growths are detected in about one out of five people. It’s also possible the CT scan will reveal something outside of the colon which could require additional testing. Stay calm and wait for your results if this happens; while these findings sometimes save lives, they can also cause unnecessary worry.
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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.
For more information about virtual colonoscopies, please call the Colon Cancer Alliance’s Toll-free Helpline at (877) 422-2030.







