Patient instructions for further bowel preparation for CT colonography

Information for patients whose initial preparation of your bowel has not been sufficient to produce a diagnostic result from your examination, a further 24 hours of additional bowel preparation is required.

Please follow these instructions to continue bowel preparation for your examination. 

Diarrhoea may occur so make sure you have easy access to a toilet. 

It is important to drink plenty of clear fluids during the entire period and aim for at least three pints of clear fluid every day. Examples of clear fluids are water, fruit squash, clear soup (e.g. Oxo, Marmite or Bovril), fizzy drinks (such as lemonade or cola), tea, or coffee. You should continue with any prescribed medication throughout.

On the day of the original appointment (today):

  • Continue Low Residue Diet (see the information below). 
  • Drink plenty of clear fluids. 
  • Prepare and drink water and Gastrografin mixture:
  1. In a glass, mix one bottle of Gastrografin (20ml) with 200ml (half a pint) of water. (You can add fruit squash/cordial if you prefer). 
  2. Drink the mixture with a meal.

Day of re-booked examination:

  • Please drink plenty of clear fluids. 
  • No solid food. 
  • Prepare and drink water and Gastrografin mixture: 
  1. In a glass mix one bottle of Gastrografin (20ml) with 200ml (half a pint) of water. (You can add fruit squash/cordial if you prefer). 
  2. Drink this mixture at least 2 hours before your new appointment time.

Low Residue Diet for CT Colonography preparation

Please continue this diet to prepare for your new appointment. Eat no solid food on the day of your new appointment.

You will be given further advice if you are undergoing other treatments such as dialysis. If you are diabetic avoid all foods marked with a *.

Foods allowed

  • White flour: cornflour, custard powder, arrowroot, tapioca, sago, semolina. 
  • White pasta: spaghetti, macaroni, other pasta shapes and noodles, tinned spaghetti in sauce. 
  • White breads: pitta bread, soda bread, naan bread. (Except high fibre white breads). 
  • White rice: any types. 
  • Potatoes: peeled or cooked in any way but don’t eat the skin. 
  • Fruit and tomato juice. 
  • Breakfast cereals: cornflakes, Rice Krispies, Frosties*, Honey Smacks*, Ricicles*, Coco Pops*, Special K. 
  • Biscuits*: any made with white flour e.g. rich tea. 
  • Cakes*: any made with white flour e.g. sponge, plain scones, doughnuts. 
  • Milk, plain yoghurt, all cheese, cream, butter, ice cream, plain fromage frais. 
  • Eggs. 
  • Fish. 
  • Texturised vegetable protein (e.g. Quorn). 
  • All oils, margarine, low fat spread, and butter. 
  • All drinks including tea, coffee, squash, fizzy drinks, cocoa, drinking chocolate, malted drinks. 
  • Sugar*, golden syrup*, treacle*, honey*, fruit sweets*, choco-toffee*, jelly jam*, jelly marmalade*, jelly*, fruit sorbets*. 
  • All meat including tinned and corned.

Foods not allowed

  • Wholemeal, brown, rye flours and bran. 
  • All wholemeal pasta including spinach flavoured, lasagna verdi, wholemeal spaghetti in sauce.
  • Wholemeal, brown, granary, high-fibre white, malt breads, poppadums and wholemeal pitta breads.
  • Wholegrain rice, wild rice, and barley. 
  • All other vegetables including baked beans, other pulses, tinned tomato, crisps, potato snacks.
  • Breakfast cereals: Shredded Wheat, Shreddies, Bran Flakes, All Bran, Alpen and other muesli, Farmhouse Bran, Oat Crunchies, Start, Ready Brek, porridge, and oatmeal. 
  • Cakes: made with wholemeal flours including pastries, pies, and wholemeal crumbles. 
  • All fruit including fresh, frozen, stewed, canned, and dried e.g. raisins and currants. 
  • Fruit, muesli, and nut yoghurts. 
  • All nuts and seeds, including peanut butter, hummus, tahini, marzipan.
  • All dietary supplements that come as a tablet e.g. vitamins, glucosamine, and herbal extracts. 
  • All alcoholic drinks. 
  • Sweet mincemeat, jam with seeds, ordinary marmalade, chocolate made fruit and nuts, fruit in jelly.
  • Meat pies, pasties, puddings if made with wholemeal flour. 
  • Meat dishes which contain vegetables e.g. curries, casseroles, chilli-con-carne.

© North Bristol NHS Trust. This edition published December 2024. Review due December 2027. NBT003567.

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Imaging Department Contact Centre

If you are unable to attend your appointment please let us know as soon as possible. You can also contact the Imaging Department Contact Centre if you wish to change or discuss your appointment.

Telephone: 0117 414 8989

Patient instructions for further bowel preparation for CT colonography