CT colonography (CTC)

CT colonography (CTC), also known as a virtual colonoscopy, is a minimally invasive imaging test that examines the inside of your bowel using a specialised CT scanner. This test provides detailed 2D and 3D images of your colon and rectum, helping to diagnose conditions such as:

• Bowel cancer

• Colonic polyps

• Inflammatory bowel disease (IBD)

• Diverticular disease

 

Unlike a traditional colonoscopy, CTC does not require the insertion of a camera into the bowel, making it a quicker and less invasive alternative for some patients.

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Do you need any preparation beforehand?

For the scan to produce clear and accurate images, your bowel must be completely empty. You will receive:

• Laxative sachets (usually Picolax) to take the day before the procedure

• Instructions to avoid eating or drinking from midnight before the examination

• Guidance on taking normal medications—you can usually continue them as usual

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Proper bowel preparation is essential for a successful scan, so following the instructions carefully is important.

 

What does the CT colonography scan involve?

• Changing into a hospital gown - you may be asked to remove some clothing for the scan

• Placing a cannula - a small tube (cannula) is inserted into a vein in your arm to allow the contrast dye to be given, improving the visibility of your organs and blood vessels

• Inflating the bowel—a small tube is gently inserted into your rectum to introduce air, expanding the bowel for clearer images

• Administering an injection - a muscle relaxant (Buscopan) is sometimes given to relax the bowel and reduce cramping

• Scanning process—you will lie on a moving examination table, which passes through the doughnut-shaped CT scanner. The machine will take hundreds of cross-sectional images, which are reconstructed into 3D images to provide a detailed view of your bowel

 

The procedure is quick and painless, usually lasting around 15 to 20 minutes.

 

What happens after the test?

• You can eat and drink normally once the scan is complete

• You may experience mild bloating or wind-like discomfort, but this usually settles quickly

• The scan results will be reviewed by a specialist, and a detailed report will be sent to your consultant

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If polyps or abnormalities are found, your consultant may recommend a colonoscopy for further assessment or biopsy if needed.

 

What are the benefits of CT colonography?

• Less invasive than a traditional colonoscopy - no need for a camera to be inserted into the entire bowel

• Highly detailed 3D imaging - helps to detect polyps and cancers at an early stage

• Short procedure time - typically takes around 15 to 20 minutes

• Minimal recovery time - no sedation is required, so you can resume normal activities immediately

 

CTC is an excellent alternative to colonoscopy for patients who are not suitable for an endoscopic procedure or prefer a less invasive option.

 

Are there any risks?

CT colonography is a safe and commonly performed test. However, there are some minor risks

• Mild bloating or cramping due to the air introduced into the bowel

• Rare allergic reaction to the contrast dye (inform your doctor if you have any allergies)

• Minimal radiation exposure, similar to other CT scans

 

If you experience severe pain, unusual bleeding, or allergic reactions, contact us immediately.