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This section contains answers to frequently asked questions about this topic. Questions have been suggested by health professionals, website feedback and requests via email.

What should I eat and drink before a colonoscopy?


Your doctor will usually ask you to eat low-fibre foods in the two days before your colonoscopy. The day before the procedure you will need to only drink clear liquids. This is to make sure your bowel is empty so that your doctor can see it clearly during the test.


A colonoscopy is a test that allows your doctor to look inside your large bowel. In order for your doctor to see it clearly, it needs to be completely empty. To do this you will probably be asked to change what you eat and drink in the two days before the procedure.

Your doctor will ask you not to eat any high-fibre foods for two days before your colonoscopy. High-fibre foods include most fruit and vegetables, wholemeal bread and pasta, brown rice, pulses and nuts. Instead you will need to stick to low-fibre foods such as lean meat, fish, boiled potatoes without the skin and white bread, pasta and rice. You will also be asked to drink clear fluids only. This means fluids that don’t contain milk such as water, squash, clear soup, meat extract drinks, strained fruit juice, lemonade, jelly (not containing fruit) and tea and coffee (without milk).

The day before your colonoscopy you will need to stop eating solid foods and have only clear fluids.

You will receive full instructions before your colonoscopy appointment, which you should follow carefully.

Will I need to have a colonoscopy as part of screening for bowel cancer?


Bowel cancer screening aims to find cancer when it’s in the early stages. If blood is found in your faeces (stool) during the first stage of screening, you may be offered a colonoscopy to look at the inside of your bowel.


Bowel cancer screening aims to find bowel cancer when it’s in the early stages and treatment is more likely to be effective. Screening is offered to all men and women between the ages of 60 and 69 in England and Northern Ireland. In Scotland it’s offered to people aged 50 to 74 and in Wales to anyone aged between 60 and 74. If you’re eligible for screening, you will be offered a test every two years.

Everyone is offered a test called faecal occult blood (FOB) testing. The test checks for blood in your faeces, which is one of the possible signs of bowel cancer. You will be sent a testing kit and instructions that show you how to take a sample of your faeces. You send this to a laboratory and should usually get the results back within two weeks.

Out of every 100 people who do the test, about 98 have a normal result. If you have an unclear or abnormal result, it probably means that blood has been found in your faeces. You will be offered more tests to find out what is causing this. One of the tests you may have is a colonoscopy. It’s important to remember that any blood in your faeces may be caused by conditions other than cancer.

If you would like more information about bowel cancer screening, or are worried about your test results, talk to your GP or nurse.

What are polyps and why do they have to be removed?


Polyps are growths inside your bowel. They are quite common and usually don’t cause any problems. However, certain types of polyps can grow into cancers over time so if your doctor finds any polyps during your colonoscopy, he or she will probably remove them.


Polyps are small, fleshy lumps, usually less than 1cm in size, although they can be bigger. About twenty-five in every 100 people develops a polyp in their lifetime, most often after the age of 60. Men are slightly more likely to develop polyps than women.

Some polyps are attached to the side of your bowel on a stalk and look a bit like a mushroom, whereas others are flatter and have no stalk. You may have just one polyp, or several.

Most polyps never cause any problems. However, there is a small chance that over time a type of polyp known as an adenoma will grow into a cancer. It’s now thought that bowel cancer starts as a polyp so if your doctor finds any during your colonoscopy, he or she will probably remove them.

Some people develop a certain type of polyp that can multiply over time. For this reason, you may be asked to have regular colonoscopies. How often you have these will depend on how many polyps you have had and when a polyp was last found.

Produced by Polly Kerr, Bupa Health Information Team, February 2013.

For our main content on this topic, see Information.

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  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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