CT Colonography

CT (Computerised Tomography) Colonography is a special CT (CAT) scan that can be used to obtain an “inside” view of the colon (large bowel).

It is used to examine the colon (large bowel) as an alternative to colonoscopy (a scope test of the colon) or after colonoscopy if the scope test has been incomplete or unsuccessful. 

It is the least invasive test that we have to directly identify colon polyps (possibly pre-cancerous findings in the colon) and cancers. By picking up polyps and cancers early we can either prevent colon cancer developing or improve outcome and save lives in those who are diagnosed with colon cancer

Preparing for your Appointment

When you make the appointment you will be given detailed information about the test. This will include a list of some drinks to take to prepare the bowel the day before the test, as well as special instructions about what to do the day before the test. As part of your preparation, you will be taking a laxative, a low residue (low fibre diet) and fasting from midnight the night before the test. 

Patient Instructions

What will I experience during my scan?

CT exams are generally painless, fast and easy. With multi-detector CT, the amount of time that the patient needs to lie still for is reduced.

The entire procedure takes approximately 20 minutes in the CT scanner room and the time spent in the hospital should be no more than 1-1.5 hours in total. 

On the day of your test you will check in at the Radiology Department and you will be changed into a gown. In the CT room the doctor will explain the test to you.

At the start of the test, you will need to lie on your side on the scanner table. A short, soft tube is then placed into the back passage (rectum) and some gas (carbon dioxide) will be gently puffed through this tube into the colon so that the colon can be observed on the CT scan. At this time, you may experience mild bloating and cramps in your tummy. You may be given a small injection of a medicine called buscopan which minimises these bowel cramps.

Following insertion of the tube, you will be placed lying on your back, with the tube remaining in position. When the first scan is complete you will then need to turn onto your front while the tube remains in position. A second scan will then be performed. After this the tube will be removed.

Special light lines may be seen projected onto your body, and are used to ensure that you are properly positioned. With modern CT scanners, you will hear only slight buzzing, clicking and whirring sounds as the CT scanner's internal parts, not usually visible to you, revolve around you during the imaging process.

You will be alone in the examination room during the CT scan, unless due to specific circumstances you require someone present. The radiographer will always be able to see, hear and speak with you through a built-in intercom system.

As you will not require any sedation, there is no recovery period required. Once the test is complete, you will be free to leave the hospital and resume your normal activities. 

You CT colonography results will be reviewed and reported on by a Consultant Radiologist specially trained in CT Colongraphy. The full report will be sent to your referring physician, who will discuss the results with you.