What is Colonography?

It is a CT scan of your abdomen specifically examining your large bowel or colon.

How does the equipment work?

The CT scanner is a large square machine with a circular hole or gantry, sometimes described as looking like a “donut”. You lie on the examination bed which moves gently into the scanner.  The MRT (Medical Radiation Technologist) takes x-rays through the abdomen and a powerful computer produces images which are manipulated to create a virtual ‘fly through’ of the colon.  You are able to contact the MRT at any time via an intercom.

Specialist Radiologists review the many images on a workstation and generate a report.


What are the risks?

There is a very small risk that inflation of the colon with air could injure or perforate the bowel.  This happens in fewer than 1 in 10,000 people. The estimated lifetime cancer risk associated with exposure to the amount of radiation used in CT Colonography scan for a 50 year old person is about 0.14%. 

What are the advantages?


  • An excellent alternative examination for failed or incomplete colonoscopy
  • Accurate - research studies have shown CT Colonography scans to be 97.7% sensitive to detecting cancer, whereas barium enema studies only 63.7% (Thomas, Atchley & Higginson, 2009).
  • Safe - minimal chance of bowel perforation
  • Images organs outside the bowel - the liver, kidneys and other organs in the abdomen are also assessed.
  • Cost effective
  • Well tolerated - sedation and pain-relievers are not needed and therefore no recovery period is necessary
  • Short examination time - less than other colon examinations

This appointment generally takes about 45 minutes.


Download Information Sheet

Pre Examination

Before your Examination

Please come to one of our practices to make your appointment and receive information about the procedure.  We will discuss:

  • Bowel preparation - to give us the best view of your bowel, it is emptied by using a laxative and a special diet that will start two days before the test. The laxatives and a diet sheet with instructions will be given to you by the receptionist upon making your appointment

  • Details about the examination itself

  • Medical insurance and ACC queries

  • Post examination information will be given

Your Examination

You will be asked to change into a gown.

To enable us to see the wall of the colon fully the colon is filled with air by passing a thin plastic tube or catheter into your back passage and gently pushing in air. The MRT will be with you during this procedure.

The vast majority of patients who have the scan report a feeling of fullness when the colon is filled with air during the test, as if they need to pass wind. You must try to hold on to the air.

You will be given an intravenous injection in your arm that is a muscle relaxant (Buscopan). This will relax the bowel and ease any discomfort, such as stomach cramps, that you may feel.

Two CT scans are performed, one where you are positioned on your back, and another lying on your stomach. Once the scans are completed, the catheter is removed and you will be shown to the bathroom. 

Post Examination

You will be asked to change back into your clothes, your items will be returned to you and you will be monitored for 10 minutes. After the examination you may eat and drink, as well as drive, as normal. You may experience slight cramping discomfort for a few hours after the test.

Your images will be interpreted by the radiologist and a report sent directly to your doctor who will discuss the results with you.