CT Scans with Bowel Preparation

What is a CT scan?

A CT scan is an examination of any part of your body using a Computed Tomography scanner (CT scanner), which provides accurate pictures of the structures inside your body using x-rays. The scan taken builds up many images of the body, rather like the slices of a loaf of bread. It helps the doctor investigate your symptoms.

How do I get ready for a CT scan with bowel preparation?

Yes, this examination requires you to follow a special diet and take some bowel preparation at home for 2-3 days before the scan appointment. The bowel preparation and diet instructions will be couriered to you along with your CT scan appointment letter. Please follow the instructions very carefully in order to get the best information from the scan pictures.
It is very important to stay well hydrated by drinking lots of fluids whilst you are taking the preparation in the days leading up to your scan.
The special diet required is called a low fibre diet and is designed to reduce the amount of food waste within the bowel before the scan.
You will be asked to eat low fibre foods including the following for 2 days before your scan:
  • Milk (2 cups per day), plain yoghurt, cheese, butter, margarine
  • White fish or chicken (boiled, steamed or grilled)
  • Eggs, Tofu , white pasta, white rice
  • White bread, white pitta, white flour chapattis
  • Potatoes with no skin (mashed, boiled)
  • Clear soups (no solid bits - e.g. sieved chicken noodle), Bovril, Oxo
  • Clear jelly, boiled sweets, ice cream, chocolate (no fruit or nut pieces)
  • Salt, pepper, sugar, sweeteners and honey

Have plenty to drink from tea, coffee, squash, fizzy drinks, water, clear fruit juices (e.g. - apple, grape, cranberry).

Suggested meals
could include for example:
Breakfast:  White bread/toast with butter and honey, boiled or poached egg
Lunch/ Dinner: Grilled fish or chicken with white rice and boiled potatoes (no skin), scrambled eggs on white toast, vanilla ice cream
Do not eat high fibre foods such as red meats, pink fish ( salmon/mackerel), fruit, vegetables, salad, mushrooms, sweetcorn, cereals, nuts, seeds, pips, bran, beans, lentils, brown bread, brown or wild rice, brown pasta, pickles or chutneys.
On the day of your appointment you may drink water, but please do not eat or drink anything else (diabetic patients may eat non-solid food from the diet sheet).

Are there any risks?

This is a safe examination, however there is some risk associated with most procedures.
If you are diabetic, please monitor your blood sugar carefully during the bowel preparation. Seek medical advice if you feel unwell.
  • There is a small risk with the exposure to radiation as with any x-ray examination
  • There is a small risk of having an allergic reaction to the contrast (x-ray ‘dye’) in some people. Please inform the CT radiographer on 020 7288 3318 if you have an allergy to iodine or have had an allergic reaction to contrast in the past
  • You may experience a metallic taste, hot flush or a sensation of passing urine during the injection, this is normal and will pass quickly
  • You should drink plenty of water/fluids before and after the examination, particularly if you have had any recent episodes of vomiting or diarrhoea
  • Occasionally, some patients experience a mild rash, itchiness or nausea. Inform a radiographer if this happens on the day of your scan

Please talk to your doctor or radiographer if you have any concerns about the risks. You can also access more information about radiation doses on the gov.uk site by clicking here

What happens during a CT scan with bowel preparation?

You will be asked to change into a gown which is provided. The radiographer (who operates the scanner) will take you into the scanning room where you will lie on a scan table.
You may be given an injection to relax the bowel, which makes the examination more comfortable and effective. You will also be given an injection of contrast (x-ray ‘dye’) during the scan to enhance the images. Both injections will be given through the same needle.
When you are lying comfortably on your side, the radiographer will gently pass a very small flexible tube into the back passage, and distend the bowel with air, so that it can be seen more clearly on the scan. It may be uncomfortable, although not usually painful. This tube will remain in place during the scan.
Pictures will then be taken with you first lying on your back and then on your tummy. The table moves slowly through the scanner, which is shaped like a large ring.
You can talk to the radiographer via a microphone and they can talk to you and see you throughout the scan. You may be asked to hold your breath for approximately 10 seconds whilst pictures are taken.
The scan itself takes about 30 minutes but you will be in the department for up to 1 hour. Please allow for this when considering your transport to and from the hospital.

What happens after a CT scan with bowel preparation?

The scan is reported by a radiologist and the report is sent to the doctor in clinic who requested the scan.  The report will only go to your GP if they have requested the scan.
Typically, you will receive the results of the scan the next time you visit the doctor looking after you.  Your doctor will be able discuss what future tests or treatment you may need.
Last updated17 Feb 2021
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