Virtual Colonoscopy - Topic Overview
What is a virtual colonoscopy?
colonoscopy uses computed tomography (CT) or
magnetic resonance imaging (MRI) to make a
three-dimensional image of the interior lining of your
large intestine (colon) and rectum. A virtual colonoscopy can be used to
screen for precancerous and cancerous growths in the colon or rectum (colorectal cancer), such as
polyps or tumors.
Virtual colonoscopy (also called computed tomographic
colonography, or CTC) is still being studied to determine whether the results
are as accurate as a
regular colonoscopy. Virtual colonoscopy is not yet
Virtual colonoscopy is one of many tests that may be used to screen for colon cancer. Which screening test you choose depends on your risk, your preference, and your doctor. Talk to your doctor about what puts you at risk and what test is best for you.
For more information on screening tests for
colon cancer, see:
- Colon Cancer: Which Screening Test Should I Have?
Why is it done?
A virtual colonoscopy may be done
- Screen for colorectal cancer or
- Monitor the growth of polyps.
- Screen for recurrence of colorectal cancer in people who have
had surgery for this disease.
- Evaluate abnormal results from other
- Replace a regular colonoscopy if the thin lighted
scope cannot be inserted in the colon for some reason, such as when a tumor
blocks the passage.
Virtual colonoscopy is not commonly done for other
conditions at this time but may prove to be useful to:
- Detect other problems or diseases of the
anus, rectum, or large intestine (colon).
- Check the source of
- Check the cause of chronic
- Monitor the treatment of inflammatory bowel
How do I prepare for it?
requires the same cleansing colon prep as a regular colonoscopy. Your doctor will tell you what to do before the test.
If you are having virtual colonoscopy using CT, you will be given some liquid to drink after your bowel prep. This drink is a contrast medium that makes the large intestine easier to see in the pictures.