CT Colonography (CTC)- A guide to your scan

What is Computed Tomography Colonography (CTC)?

Computed tomography Colonography (CTC) is a CT scan that looks at the large bowel (colon) and abdomen.

A thin tube will be inserted into your rectum. Carbon dioxide gas is passed through the tube to distend (expand) your colon. A CT scan is then performed to take pictures of your bowel.

You will be in the scan room for up to 45 minutes, and the scan itself usually takes around 15 minutes.

Who will perform the test?

A senior radiographer trained to undertake the CTC procedure.

How do I prepare for the test?

You will need to start the preparation two days before your appointment.

A special (low residue) diet is very important along with the liquid bowel preparation (Gastrografin). Gastrografin is a clear, aniseed tasting liquid which contains iodine which should be drunk neat. It has a slight laxative effect so you may want to be close to a toilet after you have taken it as it often causes frequent loose bowel motions.

It is designed to allow us to clearly see faeces in your colon, this is called faecal tagging.

It helps us see your colon and its contents clearly.

If you have had a severe allergic reaction to x-ray contrast or iodine in the past then please do not drink the Gastrografin.

Do not be alarmed if you haven’t been to the toilet many times after drinking the liquid, your test can still be performed.

If you take iron tablets please stop taking these four days before your appointment.

‍Do not stop taking vital medication such as steroids, diabetic drugs or heart drugs.

‍If you have diabetes and are taking medication, please see the attached guidance sheet for instructions relating to your medication.

Bowel preparation for CT Colonography

A special diet, has been designed to prepare and cleanse your colon before your examination. It is important to follow this diet properly because excess faeces in your bowel can make it difficult for the doctor looking at the scan to interpret it.

Bowel preparation for CT Colonography

• Ideally all diabetic patients will be given an early morning appointment
• You will be offered a hot drink after the examination.You are welcome to bring a snack with you to eat after the test. As a diabetic, you are at risk of having a ‘hypo’ (hypo-glycaemic episode/low blood sugar) if you go without food for any length of time. ‘Hypo’ symptoms \include sweating, shakiness, blurred vision, dizziness and confusion. To avoid this, please check your blood sugar regularly if you are able. While you are drinking the Gastrografin liquid, you are allowed clear fluids at anytime. Clear fluids include sugary drinks such as Lucozade, fizzy drinks and fruit juices.
• Please do not bring any valuable possessions, such as jewellery or watches to your appointment. You may be asked to remove all jewellery during your appointment and these items will remain your responsibility.
• We also ask that you avoid wearing long flowing articles of clothing and that suitable footwear is worn to ensure your safety when attending for your scan. Please note that your scan maybe conducted on one of our mobile units which can involve access via metal steps and/or a patient lift.

What happens during the test?

You will be asked to change into a hospital gown on your arrival at the department. member of staff will put a needle (cannula) into a vein in your arm. This is so that a muscle relaxant (Buscopan) and x-ray contrast medium can be injected during the scan. We will ask you some questions and explain the procedure to you so that you understand what is happening. You can also ask us questions at any time.

A small tube is inserted into your rectum and your colon is filled with carbon dioxide gas using a special machine.

Two scans are then performed, one with you lying on your front and a second with you lying on your back. Occasionally a third scan may be needed so that we can see the whole of the large bowel clearly and this may be taken on your side.

Are there side effects or risks from the procedure?

CT scanning uses X-ray radiation. Exposure to X-ray radiation could slightly increase your chances of developing cancer many years later, although standard CT scans use low doses of radiation so this risk is estimated to be very small. The amount of radiation you are exposed to during a CT scan is equivalent to between a few years exposure to natural background radiation for the environment. The doctor who has referred you for this procedure has decided that the benefits of the scan outweigh the risks.

If you are or think you may be pregnant, you should tell us before your scan.

The contrast injection may cause you to feel a warm sensation passing around your body.

Mild abdominal discomfort and bloating can occur when gas goes into the colon. We use carbon dioxide gas because the body quickly absorbs it.

Any symptoms quickly pass when the tubing is removed from the rectum and you have gone to the toilet.

Buscopan (muscle relaxant) can make your mouth dry and your vision slightly blurred, which normally lasts for 15-20minutes.

Very rarely patients may develop pain or redness of the eyes which occurs in the 24 hours after the test. If this happens, you should go to an Accident & Emergency department immediately for a check up.

Please remember that this is very rare.

‍Perforation of the bowel can occur with this test but this is also very rare (approx 1 in 3000 tests). When it happens most cases resolve without treatment, but it may require hospital admission and observation under the care of a surgeon.

Despite these small risks, your doctor believes it is advisable that you should have this examination.

Please remember this test is safe - serious complications are rare.

How will I get my results?

You will not be given any results on the day of your scan. The images will be sent for reporting and you will be contacted by your consultant when the results are available.

Can I eat normally after the test?

Yes, eat normally but still drink plenty of fluid for the next day or so as you may still be dehydrated. Tea or coffee and a biscuit will be offered after your scan, but consider bringing a snack with you to eat afterwards as you may be hungry after fasting.

Frequently asked questions

What do I do if I don’t open my bowels after drinking the Gastrografin liquid?

Don’t worry, as long as you drink the liquid your test will still be able to be carried out.

What if I have a known allergy to the Gastrografin?

Do not drink the liquid and contact the number on your appointment letter as soon as possible.

Can I take my normal medications?

Yes, everything except for iron tablets, which you need to stop taking for four days before your appointment. If you are diabetic please read the earlier section. Do not stop taking vital drugs – please refer back to the diabetes information if this affects you.

Will the test be painful?

No, but you may experience some mild abdominal discomfort during the test from the gas we put in your bowel.

Will I need to bring a dressing gown?

This is not essential, but if you feel more comfortable wearing a dressing gown then please bring one with you on the day of your test.

Can I drive after the test?

Yes.

Can I bring a relative or friend with me?

Yes, but they will only be allowed to go into the examination room in special circumstances (for safety reasons). Children will not be allowed into the room whilst you are having your scan and our staff are unable to care for children during an examination. Please make alternative childcare arrangements for any childcare needs.

Your Personal Data

Alliance understands that your personal data is entrusted to us and appreciate the importance of protecting and respecting your privacy.

Further information

If you have any other questions that we have not answered, please contact the phone number on your appointment letter.

If you require this information in a different format please let us know via customercare@alliance.co.uk