Bowel Screening

Preparing for a colonoscopy

People who decide to have a colonoscopy are given an appointment to have one. Before this investigation the bowel must be completely empty so that the specialist (usually a doctor or a specialist nurse) can see the lining of the bowel clearly. The specialist screening practitioner will provide detailed instructions on how to prepare the bowel. Bowel preparation includes the use of strong laxatives and dietary restrictions.

People are given various medications to ensure that the bowel is clear. Different hospitals may use different medicines. Hospitals may ask people to take one or more of the following laxatives: Senokot, Picolax, Klean-Prep or Oral Fleet, which are taken by mouth.

The screening practitioner may give people laxatives to take home, or they may be sent by post. These laxatives are usually taken during the two days before the colonoscopy, but different hospitals will have different instructions. The laxatives cause watery diarrhoea. The bowel preparation did not bother some people at all.

Some people said that the bowel preparation was worse than the colonoscopy itself. They said that the laxative tasted horrible and made them feel sick.

One woman thought that the medicines were 'absolutely foul' and tasted like very salty, dirty water. Cleaning her teeth helped to take away the taste.

One man stressed that although he had diarrhoea after taking the laxative he had no stomach cramps. However, a man with diverticulitis had to take double the normal dose to make sure that the bowel was cleared out really well, and this caused pain as well as diarrhoea.

Some people had been told to take the laxatives and then have an enema to help to clear their bowel of faeces. People were told they could have the enema at home or in hospital just before the colonoscopy. One woman asked her husband to help her with the enema because she could not see when the enema bag was empty.

People may have to change their diet before a colonoscopy, but this depends on what laxative is used. Hospitals may ask people to eat a low residue diet for a few days before the procedure. On the day before the colonoscopy people are instructed to stop eating but drink as much clear fluid as possible. Drinks allowed include black coffee, black tea, clear soup, jelly, Oxo and Bovril. Some people described how they changed their diets and listed the foods that were forbidden.

Most people did not seem to mind the change of diet but a few said they felt hungry and hated seeing others eating good food.

Some people also recalled that they had been advised to consult their doctors about taking certain medicines before the colonoscopy.

Last reviewed May 2016.

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