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Virtual Colonoscopy

June 10, 2008 - 7:30am
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Virtual Colonoscopy

(VC, CT Colonography)

Pronounced: virtual koh-luh-NAHS-kuh-pee


A virtual colonoscopy is a procedure in which x-rays and computers produce two and three dimensional images of the entire large intestine. The procedure is used to diagnose colon and bowel disease, diverticulitis, and colon polyps that could lead to cancer.

Virtual colonoscopy can be performed with computed tomography (CT) scans, which are also called CAT scans. The procedure can also be performed using magnetic resonance imaging (MRI).

Parts of the Body Involved

Virtual colonoscopy creates an image of the colon (large intestine) only.

Large Intestine


© 2008 Nucleus Medical Art, Inc.

Reasons for Procedure

Virtual colonoscopy is used to diagnose the possibility of colon cancer, diverticulitis, polyps in the colon, and diseases of the bowel and colon. The procedure is conducted preventively (without symptoms) and also to diagnose problems in patients who are experiencing symptoms.

Risk Factors for Complications During the Procedure

Pregnant woman should not undergo virtual colonoscopy because the radiation emitted during the imaging procedure can cause damage to a fetus.

What to Expect

Prior to Procedure

Before virtual colonoscopy, patients are required to:

  • Take a laxative to cleanse the bowels the day before the procedure.
  • Use a suppository to cleanse the rectum of any feces.
  • For 24 hours prior to the procedure, avoid eating solid foods.


No anesthesia is administered before or during a virtual colonoscopy.

Description of the Procedure

During the procedure:

  • You lie on a table on your back.
  • A small, thin, flexible tube is inserted into the rectum, through which air is blown into the colon. Inflating the colon with air allows a more accurate view.
  • You must hold your breath during the procedure to prevent blurring or distortion of images.
  • The table moves through the imaging device, which captures two-dimensional, cross-sectional views of the entire length of the colon. The images are displayed on a screen like a video.
  • You then flip over onto your stomach, and the procedure is repeated.

After Procedure

Once the diagnostic imaging is complete, the images stored by the scanner are converted into computer images. These images are analyzed by a radiologist to identify any abnormalities captured by the scan.

How Long Will It Take?

The procedure takes approximately 10-20 minutes.

Will It Hurt?

When air is forced into the colon, some patients experience abdominal cramping or minor discomfort.

Possible Complications

Virtual colonoscopy is a very safe procedure, with complications and side effects extremely rare. Some possible complications include:

  • The air that causes the colon to expand can cause the colon to perforate or rupture.
  • Because you are exposed to radiation during the procedure, there is a very slight risk of developing cancer related to the radiation exposure.
  • Pregnant women should avoid CT scans because they may be harmful to the fetus.

Average Hospital Stay

Virtual colonoscopy is an outpatient procedure. No hospital stay is required.

Postoperative Care

Patients may resume normal activities as soon as the procedure is completed. Patients may eat, drink, and resume physical activity immediately following the procedure.


Outcome is dependent upon the results of the procedure.

Call Your Doctor If Any of the Following Occurs

Virtual colonoscopy is a safe procedure that very rarely results in any type of side effects.


National Digestive Diseases Information Clearinghouse

Radiological Society of North America


BC Health Guide

Health Canada


Colon cancer: virtual colonoscopy. The Mayo Clinic website. Available at: http://www.mayoclinic.com/health/virtual-colonoscopy/CO00019. Accessed May 28, 2007.

Jani S. Virtual colonoscopy: are we there yet? National Cancer Institute website. Benchmarks. 2004;4(2). Available at: http://www.cancer.gov/newscenter/benchmarks-vol4-issue2/page1. Accessed May 28, 2007.

Senagore A. Computed tomographic virtual colonoscopy. American Society of Colon & Rectal Surgeons website. Available at: http://www.fascrs.org/displaycommon.cfm?an=1&subarticlenbr=232. Accessed May 28, 2007.

Last reviewed May 2008 by Daus Mahnke, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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