Loading icon
Press enter or spacebar to select a desired language.
Health Information Center

CT Colonography

  • Cynthia M. Johnson, MA
Publication Type:


CT Colonography

(Computed Tomography Colonography; Virtual Colonoscopy)


CT colonography is a radiology test that looks at the colon (large intestine).

Reasons for Test

This test is done to look for polyps or colon cancer.

Colon Polyps.

Nucleus Imagehttp://services.epnet.com/getimage.aspx?imageiid=77277727si55551476.jpgsi55551476.jpgNULLjpgsi55551476.jpgNULL\\hgfiler01a\intellect\images\si55551476.jpgNULL54NULL2008-12-10251313Copyright © Nucleus Medical Media, Inc.

Possible Complications

This procedure is safe. Rarely, a person may be allergic to the contrast material that is sometimes used.

What to Expect

Problems to Look Out For

Call your doctor if you have any problems, such as:

  • Nausea
  • Itching
  • Problems breathing

If you think you have an emergency, call for medical help right away.

Prior to Test

The surgical team may meet with you to talk about:

  • Any allergies you may have
  • Current medicines, herbs, and supplements that you take and whether you need to stop taking them before the procedure
  • Fasting before surgery, such as avoiding food or drink after midnight the night before
  • Whether you need a ride to and from the procedure
  • Cleansing the bowel before the procedure

Description of the Test

You will be on your back on a movable x-ray table. A small tube will be inserted into your rectum. Air will be gently pumped through the tube. The table will move slowly through the donut-shaped CT scanner. You will need to remain still. You will also be asked to hold your breath for periods during the scan. The test will then be repeated with you lying on your stomach.

After Test

You will be able to leave after the test is done. You can go back to your normal diet and activities.

How Long Will It Take?

30 to 40 minutes

Will It Hurt?

You may feel cramping and bloating. You may also feel the urge to pass stool.


A specialist will review the images. A follow-up exam or more testing may be needed.





  • Bryce C, Bucaj M. CT Colonography for colorectal cancer screening. Am Fam Physician. 2021;103(1):55-56.
  • CT colonography. Radiology Info—American College of Radiology website. Available at: https://www.radiologyinfo.org/en/info/ct_colo.
  • Scalise P, Mantarro A, et al. Computed tomography colonography for the practicing radiologist: A review of current recommendations on methodology and clinical indications. World J Radiol. 2016;8(5):472-483.
  • Virtual colonoscopy. EBSCO DynaMed website. Available at: https://www.dynamed.com/procedure/virtual-colonoscopy.


  • Daniel A. Ostrovsky, MD
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.