This information leaflet has been produced to give you general information and hopes to answer most of your questions when requiring a CT Colonoscopy. It is not intended to replace the discussion between you and the healthcare team, but may act as a starting point for discussion. If after reading it you have concerns or require further explanation, please discuss this with a member of the healthcare team.
Please inform a member of the ward staff prior to your scan if:
- You have diabetes and are taking Metformin
- You are, or might be, pregnant
- You weigh more than 200kg or 31 stone
What is a CT Colonoscopy?
CT Colonoscopy is a test that uses a special x-ray machine to produce detailed pictures of your large bowel. These pictures are examined by a radiologist (a doctor who specialises in reading x-ray images) and will help diagnose if there are any problems. The CT scanner is an open ring-like structure which resembles a giant doughnut. It is not a tunnel as some people might expect.
How should I prepare for my CT Colonoscopy?
It is very important that you have an empty, clear bowel on your scan pictures. To ensure this you will be given a special diet you will need to follow on the day before the scan.
You will also be given three bottles of x-ray dye called Omnipaque to drink. This will dye any leftover stools in your bowel, so it is easily recognised and not mistaken for disease. Omnipaque does have some laxative effects and it may cause diarrhoea. Therefore, it is advisable to stay close to a toilet after taking it. It can also cause dehydration, so we recommend you drink plenty of fluids to keep yourself hydrated.
Full details of the diet and x-ray dye drink will be given to you by a nurse on the ward.
Can I take my prescribed medicines as usual?
If you take iron tablets, these will need to be stopped seven days before your procedure. You can continue to take all your usual medication as normal, unless specifically told otherwise by a doctor or nurse on the ward.
Can I bring a relative or friend?
Yes, but for safety reasons they will not be able to accompany you into the CT scan room except in very special circumstances.
What happens at the hospital before the scan?
When you arrive in the department you will be greeted by the reception team and radiology assistants.
You will be asked to change into a hospital gown. It is advisable to leave any valuables at home.
What happens during a CT Colonoscopy scan?
In the scan room the radiographer (member of the radiology team trained to carry out scans) will explain the CT examination to you and what to expect. You can ask any questions you may have.
A nurse or doctor on the ward will have already put a cannula (needle) into a vein in your arm or back of your hand on the ward. During the scan you may be given an injection of a muscle relaxant called Buscopan. This helps relax the muscles in your bowel walls. You may also be given an injection of x-ray dye (contrast). This dye highlights the blood vessels and body organs more clearly on the CT images. If you do need to have an injection of Buscopan or x-ray dye we will ask you a number of questions about your medical history.
You will be asked to lie on your side on the scanning table. A small flexible tube will be inserted into your rectum (back passage). A small balloon at the tip of the tube will be inflated to help keep the tube in place. Carbon dioxide (a harmless gas) will then be gently pumped into your bowel. During this process you may feel aches and pains in your stomach, similar to trapped wind. It may feel as if you urgently need to go to the toilet, but this is only a feeling.
You will then be asked to lie on your back. The scanning table will move your body through the ‘doughnut’ shaped hole (gantry) so that your bowel can be scanned. If you need to have x-ray dye, this will now be injected. The dye may give you a metallic taste in your mouth and a ‘hot-flush’. Some people feel as though they have an urgency to pass urine. All of these sensations pass in a couple of minutes. If you have any questions about this please ask a member of staff.
You will need to lie very still while each picture is taken, and you may be asked to hold your breath for a moment. We understand that some people have difficulty holding their breath- please tell us at the time if this is a problem for you.
The scanner is not noisy, and the examination should not be painful. During the scan, the radiographer and the radiology assistant will be in a control room close to the scanner. You will be able to talk to them on an intercom and you will be observed at all times.
The radiographer will then ask you to turn over on your front or side and the scan will be repeated.
Once the scans have been completed, the radiographer will remove the tube from your rectum. You will be able to go to the toilet at this time should you feel the need.
How long does the scan take?
The actual scan itself usually lasts between 20 and 30 minutes but you will be in the department 45 to 60 minutes.
We will try and keep to your appointment time but occasionally we have to scan patients urgently at short notice. This means your appointment could be delayed. We will let you know if this is the case.
Are there any risks?
As with x-rays, CT scans use radiation. The level of radiation is small, and the benefits of the scan are thought to outweigh any risks.
The Buscopan injection can make your mouth dry, vision blurred and increase your heart rate significantly. In very rare cases you may develop painful and red eyes, which is an indication of a pre-existing condition called narrow angle glaucoma.
The x-ray dye injection contains iodine which can cause an allergic reaction in a few people. You should tell the radiographer if you have had an allergic reaction to iodine or x-ray dye in the past or if you have any other allergies.
Very rarely the x-ray dye may cause kidney damage, most commonly in people known to have kidney problems. The risks will have been assessed by your doctor. Occasionally precautions may be taken prior to your scan, and you will be informed of this by our CT appointments team or radiology nurses.
Rarely, after an injection, the x-ray dye can leak outside the vein and cause temporary swelling and discomfort in the arm requiring a cold compress. Very rarely a more extensive injury to the skin and soft tissue at the injection site can occur. This is unlikely to happen but if it does we will give you further instructions and advice.
There is a small risk (approximately 1 in 3000) that your bowel could perforate (tear)with this test. If this happens it usually resolves without treatment, but may require hospital admission and observation under the care of a surgeon.
Despite these slight risks, your doctor believes it is advisable that you should have this examination. Please bear in mind that there may be greater risks from missing a serious disorder by not having your scan.
What happens after the examination?
As soon as the scan is finished you can go back to the ward. You can eat and drink as normal. We will also advise you to slightly increase your fluid uptake for the rest of the day.
How do I find out the results of my scan?
The doctor who asked us to perform your test will receive your results, which is usually within seven days (sooner if admitted in hospital).
The hospital will contact you with a follow-up outpatient appointment if required. If after three weeks they have not contacted you, please contact the hospital switchboard on (0191) 482 0000 and ask to speak to your consultant’s secretary.
Who do I contact if I have concerns?
Should you require further advice on the issues contained in this leaflet, please speak to a nurse or doctor on the ward.