CT Colonography


CT colonography is a radiology test that looks at your large intestines, also called your colon. It is one of many options for colon cancer screenings.

Reasons for Test

This test is used to look for polyps or cancers of the colon.

Colon Polyps
Nucleus Image
Copyright © Nucleus Medical Media, Inc.

Possible Complications

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

Prior to Test

  • Do not eat for 8-12 hours prior to the test.
  • A bowel cleansing will be done with a laxative. The goal of the cleansing is to rid your colon of all stool. The laxative will cause you to have many bowel movements over several hours.
  • If you have diabetes, talk to your doctor about adjusting your medications.

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

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

How Long Will It Take?

30-40 minutes

Will It Hurt?

You may feel cramping and bloating. You may feel the urge to have a bowel movement.


An expert will review the images. If something abnormal is seen, your doctor may suggest a colonoscopy .

Call Your Doctor

If you were given contrast, call your doctor if you notice:

  • Nausea
  • Itching
  • Difficulty breathing

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


Please note, not all procedures included in this resource library are available at Allegiance Health or performed by Allegiance Health physicians.

All EBSCO Publishing proprietary, consumer health and medical information found on this site is accredited by URAC. URAC's Health Web Site Accreditation Program requires compliance with 53 rigorous standards of quality and accountability, verified by independent audits. To send comments or feedback to our Editorial Team regarding the content please email us at HLEditorialTeam@ebscohost.com.

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.

Editorial Policy | Privacy Policy | Terms and Conditions | Support
Copyright © 2008 EBSCO Publishing. All rights reserved.

Colon cancer screens can prevent colon cancer by finding and removing growths before they turn into cancer. Screens also find colon cancer early, while it’s easiest to treat.