Gastrografin Preparation Sheet for CT Colonography (Afternoon Appointments)

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Afternoon Appointments Information

Important: If you no longer require this test or have recently had your bowel investigated, please let us know as soon as possible on 07826 513567

Your appointment date and time are shown on your appointment letter, sent separately. Please report to the CT reception in the X-ray department at the hospital where you are appointed, bringing this document with you.

You will need to stay close to a toilet on the day before the examination as the Gastrografin may have a laxative effect which can be extremely effective. 

If you are taking iron tablets please stop taking them 3 days before your scan. 

Please continue taking all other prescribed medications. If you have diabetes, please read the additional information provided.

You should have received a bottle of Gastrografin to drink as described below.

DO NOT drink the Gastrografin:

  • If you have previously had an allergic reaction to intravenous iodine-based contrast medium (X-ray dye injection). 
  • If you have difficulty in swallowing.

If so, please contact us on 07770 784911 Monday to Friday 9.00 a.m. to 4.00 p.m.

You will be asked to change into a hospital gown for the test, so you may wish to bring a dressing gown or coat with you to wear over the gown. 

If there is any chance of being pregnant, please notify the department. If you take oral contraceptives, the diarrhoea may reduce their effectiveness. Continue taking oral contraceptives but use other precautions for the remainder of that cycle.

The DAY BEFORE your scan

YOU MAY eat a light, LOW FIBRE breakfast (BEFORE 10.00 a.m.) from the list of foods below:

  • Milk, Plain yoghurt, cheese, butter, margarine, honey, cornflakes, puffed rice cereal, eggs, tofu.
  • White bread, white pitta, white flour chapattis, white pasta, white rice
  • White fish or chicken: boiled/steamed/grilled
  • Potatoes with skin removed (mashed, boiled, chipped)
  • Clear soups (with no solid lumps e.g. sieved chicken noodle or smooth tomato) Bovril, Oxo
  • Clear jelly, boiled sweets, ice cream, chocolate (no fruit or nut pieces).
  • Salt, pepper, sugar & sweeteners.

FROM 10.00 a.m. ONWARDS, DO NOT eat any more solid food and maintain a LIQUID ONLY DIET.

From 10.00 a.m. please follow a LIQUID ONLY DIET. You can have clear soups (for example, strained chicken noodle soup, not blended soups), vegetable Bouillon, jelly, custard, ice cream and yogurt (with no lumps), Complan drinks, Bovril and Oxo drinks, water, clear juices, fizzy drinks, coffee and tea (with milk if preferred).

Drink as much tea or water as you like but take at least a quarter pint (150 ml) of fluid every hour on the hour during the daytime.

At 6.00 p.m. Drink half the bottle of Gastrografin (50 ml), mix with an equal amount of water. It may also be flavoured with fruit juice or cordial.

ON THE MORNING of your scan

At 8.00 a.m. drink the second half of the bottle of Gastrografin (50 ml), as above.

Continue following a LIQUID ONLY DIET until 11.00 a.m.

After 11.00 a.m. you may drink water or clear sugary drinks ONLY until your scan is completed.

You may be in the X-ray department for up to one hour.

After the examination: You can eat and drink normally.

Summary of your bowel preparation plan for CT Colonography

3 DAYS BEFORE your scan

Stop any iron tablets you may be taking. 

Continue all other medication and any laxatives you normally take, until you come for your scan.

THE DAY BEFORE your scan

Remember to drink plenty of fluids. 

Have a low fibre breakfast before 10.00 a.m. from the suggested list of foods.

After 10.00 a.m. do not eat any solid food and follow a liquid only diet, clear soups etc. are allowed.

At 6.00 p.m. take the first dose (50 ml) of Gastrografin as described.

ON THE DAY of your scan

At 8.00 a.m. take the second dose (50 ml) of Gastrografin as described.

Have a liquid only diet until 11.00 a.m. and then water or clear sugary drinks ONLY until after your test.

Please follow these instructions closely to make sure that your bowel is as empty as possible before the scan. Keeping to this diet will improve the accuracy of your scan.

General Trust Information

Patient Advice and Liaison Service (PALS)

PALS is a confidential service for people who would like information, help or advice about the services provided by any of our hospitals. Please call 0800 783 4372 between 9.30 a.m. and 4.30 p.m. or e-mail Please note that this service does not provide clinical advice so please contact the relevant department directly to discuss any concerns or queries about your upcoming test.

CTC GG bowel preparation MORNING appointment CMH/NPH V2.1. Created by JAM/KAS 2020. Version 2.1. Reviewed by VM October 2023. Next Review Oct 2026.

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