Computerised Tomography (CT) Colonography is a test used to look inside your bowel and abdomen.
The test uses a CT scanner to produce images of a “slice through a part of the body”.
A CT Colonography involves using a CT scanner to produce two and three dimensional images of the whole of the large bowel (colon and rectum).
You may have been referred for this test to help your doctor find out what is causing symptoms such as abdominal (tummy) pain, weight loss, a change in your usual bowel habit and blood in your faeces (stools).
Before the test you will be asked to follow a special diet, take a laxative preparation and you will be given a small bottle of x-ray dye to drink at home. The special diet and laxatives will help to empty your bowel before the test and the x-ray dye is used to coat any faeces that remain in the bowel.
There are two other ways of looking at the large bowel:
• Barium Enema
• Colonoscopy
Barium enema examinations have been available for many years but they do not provide as much information and are often more uncomfortable for patients.
A colonoscopy involves a flexible tube with a camera on the end to directly visualize the large bowel and continues to be the main test for looking at the bowel. It is more invasive than CT Colonography and usually requires sedation. However, a biopsy or sample of tissue can be taken at the same time if required.
These two tests will only give us information about your large bowel. CT Colonography also provides information about the other structures in your abdomen.
CT Colonography is regarded as a very safe test. Problems that may occur are similar to any other test for imaging the bowel.
Carbon dioxide is used to inflate your large bowel during the examination. There is a small risk that this may cause a tear (perforation). The risk of perforation is about 1 in 3000 and is lower than that of a colonoscopy.
Other possible side effects / adverse effects:
• Abdominal pain/bloating.
• Feeling faint.
• Reactions to the injected contrast agent (“x-ray dye”).
• Dehydration or an electrolyte imbalance caused by the laxatives. It is important to drink plenty of fluids.
• Most patients can continue taking their medication as normal.
• Some diabetic patients may need to stop taking their medication before their examination. Please contact the CT department on Tel: 01253 955627 for advice. You can also refer to the separate information leaflet entitled “Guidance for Diabetics undertaking a CT Colonography”.
• If you are taking Blood-thinning/ anti-coagulant tablets for example Aspirin or warfarin or clopidogrel, you may need to stop your medication before your scan. Please contact the CT department on Tel: 01253 955627 for advice.
• Everyone receives some ionising radiation every day from radioactivity in the air, food that we eat and even from space.
• Your age, size and the reason for your scan will influence the amount of radiation used.
• The main benefit of the scan is making the correct diagnosis, so you can get the treatment that is right for you. A specialist has agreed that this benefit outweighs the risk from the radiation.
If you are pregnant or think that there is a possibility that you may be pregnant, then please contact
the CT Booking Team on Tel: 01253 955627 or 953657
If an interpreter is required, this will be arranged by
the CT booking team. Please telephone 01253 955627 to notify the team.
Friends and family members are not permitted to interpret as this is against Trust policy.
Sedation or pain relief is not needed for this test. Most people find that it can be a little uncomfortable, but as soon as the test is finished the discomfort will ease.
The most important thing to do is follow the bowel preparation Instructions.
The radiographer will explain the test and answer any questions, before asking for your consent. Please let them know if you had any problems with your bowel preparation. The procedure usually takes about 30 minutes.
You may have a small tube, called a cannula, inserted into one of the veins in your arm.
• You will be asked to lie down on the scanner onto your left side.
• The radiographer or radiologist will pass a small flexible tube into your rectum (back passage).
• A muscle relaxant is often injected to avoid bowel spasm. (You must wait 1 hour before driving after this injection). • You may be given an injection of an x-ray dye via the cannula.
• Gas (carbon dioxide) will be gently introduced into your bowel through the tube in your back passage. This is done at a controlled rate by a machine specifically designed for this purpose.
• Despite the muscle relaxant you may still feel some bloating and discomfort in your abdomen.
• Once the radiographer is satisfied with the amount of gas in your bowel, CT scans will be taken with you lying in 2 positions; first on your back and then on your front or your side.
• Each scan will take about 10-20 seconds (one breath hold). Sometimes the radiographer may need to take extra scans to ensure we can fully see your entire bowel. Occasionally we will perform a scan of your chest at the same time for additional information.
What is Picolax?
Picolax is a strong laxative which is used to cleanse the bowel prior to the examination.
What is Omnipaque?
Omnipaque is a contrast media or x-ray dye and contains iodine. It will improve the quality of your CT Scan and lead to a more accurate diagnosis.
All drugs may have some side effects. Picolax and Omnipaque do have a laxative effect and will cause diarrhoea so it is advisable to stay close to a toilet.
You may experience some abdominal cramps and bloating. You may get a sore bottom due to the frequent diarrhoea, but you can use a barrier cream such as Vaseline or nappy rash creams to alleviate this.
Some people will experience headaches and nausea/vomiting. Most of these side effects are related to dehydration so it is very important to drink plenty of fluids
IMPORTANT Preparation for the examination starts two days before your appointment with a Low Residue Diet.
Please read all sections of the leaflet completely and follow the instructions in order to prepare your large bowel for the test. If you do not follow these special instructions fully, we may not be able to perform the test.
Two days before the appointment
You should follow a low residue diet consisting of the following:
• Fats (use sparingly) – butter or margarine.
• Rice – plain or boiled white rice.
• Eggs – boiled or poached.
• Meat/Fish – mince or well-cooked tender lean beef, lamb, ham or veal, pork, poultry, fish, shellfish.
• Cheese – cream, cottage cheese or cheese sauce.
• Bread – white bread or toast.
• Cereals – crisped rice cereal, cornflakes, (no bran).
• Pasta – plain macaroni, spaghetti, noodles.
• Potatoes – boiled, creamed, mashed or baked (no skin).
• Dessert – clear jelly (not red-coloured jelly).
Foods to avoid: Red meat, sausage, pies, any fruit or salads, most vegetables, potato skins, chips, wholemeal or brown bread, nuts, pulses, baked beans, wholemeal pasta, brown rice, puddings containing fruit and nuts, cakes, biscuits and Yoghurts.
From Midnight
• You should only have a liquid diet.
• DO NOT EAT ANY SOLID FOOD UNTIL AFTER THE PROCEDURE.
You CAN have clear soups, jelly, custard (made with water), complan drinks, soft drinks (not fizzy), black tea or coffee, fruit or herbal teas, oxo, bovril or marmite drinks. Sugar or sweetners can be added.
At 8am – Take the first sachet of Picolax: Mix one sachet in 3-4 dessertspoons of cold water. Stir for 2-3 minutes – the mixture will become hot. Wait 5 minutes and then dilute the solution with cold water to make half a tumbler (150mls), stir and drink the mixture.
If you take any oral medication (tablets or liquids) you should avoid taking it the hour before and for an hour after taking the Picolax.
It is important that you don’t become dehydrated – try to drink at least a cup of water/fluids every hour all day and evening. Aim to drink between 2 and 3 litres (3-5 pints).
At 3pm – take the second sachet of Picolax (prepare as before). Continue to drink clear liquids.
At 7pm – Open the Omnipaque bottle by twisting the cap. Drink the 50mls bottle of Omnipaque solution. You do not need to dilute this but can mix this with cordial if required.
You should not eat any solids or drink milk until after the procedure. You may continue to drink clear fluids until 60 minutes before the procedure.
You can continue to take your usual medications as normal unless you have been specifically advised to stop them.
Where do I go?
Please check your appointment letter for the location and time of your appointment.
Can I bring a friend or relative?
Yes you can bring a friend or relative, however they will not be able to stay with you in the scan room during the procedure due to radiation safety regulations.
You will be greeted by a radiology assistant or radiographer who will direct you to the changing rooms where you will be required to change into a gown. You may wish to bring your own dressing gown to wear over your gown as dressing gowns are not supplied by the department. You will be in the Radiology Department for approximately one to one and a half hours.
You will need to wait in the Department for approximately 20-30 minutes after your examination.
You can return to your normal eating and drinking pattern. We recommend that you drink plenty of fluids for the following 2-3 days.
Although the carbon dioxide used to inflate your bowel is absorbed quite quickly following the procedure some minor abdominal discomfort may remain for 1-2 hours. Returning to your normal diet and moving around will help to ease any remaining discomfort.
However please seek urgent medical advice (your GP or Accident and Emergency out of hours) if you experience any of the following symptoms over the next 4 days:
1.Severe abdominal pain.
2.Increasingly painful abdominal discomfort.
3.Sweating and nausea.
4.Feeling generally unwell.
You may have been given an injection of Buscopan to relax the muscles in the bowel wall during your examination. Blurring of your vision can be a side effect of this injection, although, this side effect is short lived, usually 30 minutes. If you do experience blurring please make sure your vision has returned to normal before driving.
Please refer to the separate information leaflet entitled “Guidance for Diabetics undertaking a CT Colonography”. It is important that you follow the instructions given in this booklet and if you have any questions do not hesitate to contact your diabetic nurse or General Practitioner before the procedure. Follow the instructions carefully enclosed in the leaflet before you attend your appointment.
Please alert our radiology booking team that you are diabetic as we need to ensure you have had a blood test within 3 months of your appointment.
If you answer “YES” to any of the following questions, please contact the CT Scan department on Tel. 01253 955627:
• Are you allergic to x-ray contrast agents or iodine?
• Are you taking Blood-thinning/ anti-coagulant tablets e.g. Aspirin or warfarin or chlodogrel?
• Are you a diabetic on insulin or tablets?
• Do you have any kidney disease?
• Are you or might you be pregnant?
• Are you allergic to any of the ingredients listed on the Picolax packet?
