(Computed Tomography Colonography; Virtual Colonoscopy)
by Daus Mahnke, MD
CT colonography is a radiology test that looks at the colon (large intestine). It is one of many options for colon cancer screening.
Reasons for Test TOP
This test is used to look for polyps or cancers of the colon.
Possible Complications TOP
CT colonography is safe. It can be used if you are too sick to have other forms of colon cancer screening.
In some cases, a contrast material is used. One complication may be an allergic reaction to the contrast.
What to Expect TOP
Prior to Test
Description of the Test
You will be positioned on your back on a movable x-ray table. Just before the test, a small tube will be inserted into your rectum. Air will be gently pumped through this tube. The table will move slowly though the donut-shaped CT scanner. While this is happening, you will need to lie very still. You will be asked to hold your breath during the scan. The scanning test will then be repeated with you lying on your stomach.
After Test TOP
You will be able to leave after the test is done. You can resume your normal diet and activities.
How Long Will It Take? TOP
Will It Hurt? TOP
You may feel cramping and bloating. You may feel the urge to have a bowel movement.
Call Your Doctor TOP
It is important to monitor your recovery. Alert your doctor to any problems. If any of the following occur, call your doctor:
If you think you have an emergency, call for emergency medical services right away.
American College of Gastroenterology
National Institute of Diabetes and Digestive and Kidney Diseases
Canadian Association of Gastroenterology
Canadian Cancer Society
CT colonography. Radiology Info—American College of Radiology website. Available at: https://www.radiologyinfo.org/en/info.cfm?pg=ct_colo. Updated March 17, 2016. Accessed October 3, 2017.
Fletcher RH. Colorectal cancer screening on stronger footing. NEJM. 2008;359(12):1285-1287.
Johnson CD, Chen MH, Toledano AY, et al. Accuracy of CT colonography for detection of large adenomas and cancers. NEJM. 2008;359(12): 1207-1217.
Mulhall P, Veerappan GR, Jackson JL. Meta-analysis: computed tomographic colonography. Ann Intern Med. 2005;142(8):635-650.
Yee J. Screening CT colonography. Radiol Clin North Am. 2004;42(4):757-766.
Last reviewed September 2018 by EBSCO Medical Review Board Daus Mahnke, MD
Last Updated: 9/17/2014
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