Bowel preparation for CT colongraphy (100ml Gastrografin)

This page has information for patients referred for CT colonography at North Bristol NHS Trust with a 100ml bottle of Gastrografin for preparation.

Please follow these instructions to ensure adequate bowel preparation for your examination.

To prepare your bowel for your CT Colonography you will need to drink mixtures of water and Gastrografin. The instructions for this are below. Gastrografin often causes diarrhoea. The amount of diarrhoea is very variable. Please make sure you have easy access to a toilet during this 2 day preparation period.

It is very important to drink plenty of fluid during the entire period. You may become dehydrated otherwise. It also helps ‘flush’ the bowel through. Aim to drink at least three pints of clear fluid every day. Clear fluids include water, fruit squash, clear soup, fizzy drinks, tea, or coffee.

You also need to follow a Low Residue Diet for the 2 days of preparation, which involves eating foods with little to no fibre. Eating food with fibre may result in failure of bowel preparation, which can delay your scan and/ or treatment.

While completing this preparation you should continue to take any of your normal medication as prescribed. If you normally take laxatives for constipation, continue to take these.

How to prepare your Gastrografin mixtures:

You will be given a 100ml bottle of Gastrografin and a measuring cup to make the mixture yourself at home. This will give you enough for 5 drinks over the two days before, and the day of your appointment. To prepare the Gastrografin mixture:

Pour 20ml of Gastrografin into the measuring cup then pour this from the cup into a drinking glass.
Into the same glass add at least 200ml or half a pint of water. You can add fruit squash/cordial as well if you prefer.
Stir with a spoon until mixed well.

Two days before appointment

Start Low Residue Diet.
You will have 2 Gastrografin mixtures today.
Drink one Gastrografin mixture with your morning meal.
Drink your next Gastrografin mixture with your evening meal.
Remember to drink plenty of clear fluids.

Day before appointment

You will have 2 Gastrografin mixtures today.
Drink 2 Gastrografin mixture with your morning meal.
Drink your next Gastrografin mixture with your evening meal.
Remember to drink plenty of clear fluids.

Day of appointment

You must have no solid food from midnight.
At least 2 hours before your appointment, drink 1 Gastrografin mixture.
Keep drinking plenty of clear fluids.

Low Reside Diet foods and drinks

The table below contains foods which you are not allowed to eat while preparing for a CT Colonography. Not following these instructions could result in your scan being unsuccessful and delaying your examinations and/or treatment.

Patients with diabetes should avoid all foods marked with a*. You may have sugar-free alternatives for example pure fruit spread without skin or pips, instead of jam.

Patients with kidney failure or on renal dialysis, should only select foods and drinks from the lists which are normally allowed in your diet. Keep to your normal fluid allowance.

Table of foods and drinks allowed on Low Residue Diet

Food type	Allowed	Not allowed
Flour products	White flour, custard powder, arrowroot, tapioca, sago, semolina.	Wholemeal, brown, and rye flours. Bran.
Pasta	Any white pasta including tinned in tomato sauce and noodles.	Any wholemeal pasta including spinach flavoured pasta
Rice	White rice.	Wholemeal, brown rice. Wild rice. Barley.
Potatoes	Peeled and cooked in any way. Do not eat the skin.	Crisps, potato based snacks, potato skins.
Vegetables	None	Vegetables and salad including all pulses and baked beans.
Fruit	Fruit juices. Tomato juice.	All fruit including fresh, frozen, stewed, canned, and dried (currants and raisins).
Cakes*	Cakes made with white flour e.g. sponge cakes, plain scones, doughnuts.	Made with wholemeal flours, pastries or pies. Wholemeal crumbles.
Breakfast cereals	Cornflakes, Rice Krispies, Frosties, Honey Smacks, Ricicles, Coco Pops*, Special K.	Shredded wheat, Shreddies, Bran Flakes, All Bran, Alpen and other muesli, Farmhouse Bran, Oat Crunchies, Start, Ready Brek, porridge, oatmeal.
Biscuits*	Any made with white flours e.g. Rich Tea biscuits, water biscuits.	Any made with wholemeal flour e.g. digestives, crispbreads, cereal bars.
Dairy and eggs	Eggs cooked in any way. Milk, plain yoghurt, all cheese, cream, butter, ice-cream, plain fromage frais.	Fruit, muesli and nut yoghurts.
Fish	All fish (fresh, froze, or tinned).
Meat substitutes	Any texturised vegetable protein.
Fats	Oils, margarine, low fat spread, butter.
Sweet foods*	Sugar, golden syrup, treacle, honey, fruit sweets, choco-toffee, jelly jams, jelly marmalades, jelly, fruit sorbets.	Jam with seeds, ordinary marmalade, chocolate made with fruit and nuts, fruit in jelly, sweet mincemeat.
Meat	Any meat including tinned and corned.	Meat in pies made with wholemeal flour. Meat dishes with vegetables e.g. curries, casseroles, chilli concarne.
Nuts and seeds	None	Any nuts and seeds including peanut butters, hummus, tahini and marzipan.
Dietary supplements	None	Any dietary supplements that come as a tablet e.g. vitamins, glucosamine and herbal extracts.
Drinks	All non-alcoholic drinks.	Alcoholic drinks.

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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