Skip Ribbon Commands
Skip to main content

CT Colonography Information Page

What is CT Colonography?

A CT Colonography (CTC) uses X-rays to capture images of the large intestine (or colon), to detect cancer and smaller growths (polyps). It is an alternative examination to Optical Colonoscopy (OC). Studies have shown that CTC has similar rates of detection of cancer and certain types of polyps when compared to OC, though it may not be able to pick up very small or flat polyps. 

How do I prepare for the CT Colonography Procedure?

You are to come to the Radiology Department at least 2 weeks before your scan, to perform a screening with our radiographer and to collect the medication for bowel preparation.

Preparation for scan will begin 2 days before your scan appointment date:

  • 2 Days before the scan, you should be on Low Residue Diet:
    • Lean meat
    • Porridge
    • White Bread
    • Steamed Fish
    • Boiled Potatoes
    • NO vegetable and fruits
    • NO dairy products
    • NO Oats/whole meal
  • 1 Day before the scan:
    • NO solid food, only Clear Liquids allowed
    • NO Dairy Products
    • You should also consume the colonic lavage solution and bisacodyl tables as directed by the Radiographer upon collection.
  • Day of the scan
    • DO NOT take any food before your CT scan
    • Only plain water is allowedAn intravenous cannula will be inserted on your arm before the examination commences, if necessary. 
  • An intravenous cannula will be inserted on your arm before the examination commences, if necessary. 
  • You may be asked to do a blood test for Creatinine Serum on the day of the scan, if required
    • Waiting time for results may be as long as 2 hours
  • If you are on Sodium Glucose Co-transporter 2 (SGLT-2) Inhibitors [Dapagliflozin (Forxiga/Xigduo XR), Empagliflozin (Jardiance/Jardiance Duo/Glyxambi), Canagliflozin (Invokana)], please discontinue 2 days before the procedure.
  • If you are on anti-diabetic medication, do not take it the morning of your exam.
  • If you are on any other medications, continue your medication as per normal.
  • Please contact DDR Call Centre (6321-4225) if you have an allergy to CT contrast media e.g., Iohexol, Iopamidol, Iopromide.

Frequently Asked Questions (FAQ)

What are the risks involved?

CTC is a very safe procedure. The most significant risk is perforation (tear) of the colon which is rare. If this happens, you may need surgery to repair the tear. Reactions to the dye in the vein such as allergies and kidney injury may occur, but these are usually mild and rare. The amount of radiation used to take the images is extremely low, equivalent to about 2 years of natural radiation received by everyone from the environment.

Is Medical Certificate (MC) provided?

On the day of your scan, you can request 2 days of outpatient medical leave (MC), to cover the bowel cleansing day (1 day before scan) and the day of the scan.

Why do I have to undergo this examination?

This study is to look for growths, such as polyps or cancers, in the large intestines. Early detections mean these growths can be removed. Your clinic doctor would have determined that this scan would help diagnose your condition or follow up on it.

To find out more, please call the referring clinic/doctor to better understand the necessity of undergoing your scan. You may find the contact information on our SGH (Singapore General Hospital) website.

What if I do not want to proceed with the examination?

You may drop us an email or call us (contact found below) to let us know to cancel the scan. This will allow us to free up slots for patients who need it.

Can I get any earlier appointment slot?

We try our best to give the earliest possible appointment. However, due to the limited availability of appointment slots as this is a very specialized CT scan, the waiting time for the scan can be up to 3 months later, depending on the urgency of your condition.

Who can I contact for more information?

DDR Call Centre: 6321 4225

DDR Email: