What is “bowel preparation”?

Bowel preparation is undertaken to empty and clean out the bowel, prior to a colonoscopy. When a colonoscopy is undertaken, it is essential that the bowel is thoroughly emptied of all solid matter. Once cleaned out, the bowel lining can be seen clearly to allow for a careful examination of the colon. A good bowel preparation is vital to ensure an accurate and complete procedure. If the bowel is not completely clean and empty, the procedure may need to be postponed or repeated or lesions such a polyps or cancers may be missed.

Good Bowel Preparation
Good Bowel Preparation
Poor Bowel Preparation
Poor Bowel Preparation

How is bowel preparation undertaken?

Your doctor will give you specific information about what preparation is best for you, including information about how to modify your diet and when to take the laxative medications.

a) Modify your diet
– You may need to change your diet for several days before your procedure, or just on the day before. You should stop all seeds (multigrain bread, tomatoes, passionfruit, corn…), you may be asked to reduce your fibre intake or to have only white foods.
– You will be advised when you need to stop eating solid food and consume only clear fluids. These are liquids you can see through such as water, cordial drinks, apple juice, lemonade, sports drinks (but avoid brightly coloured drinks), clear soups such as beef broth, clear jelly or soda water. It is very important to drink more fluid than usual, to avoid dehydration and to improve the final bowel preparation.

b) Laxative medications
– You will be advised what laxative medications you need to take and when to take them. They come either as a powder that needs to be mixed in water or as tablets. They will cause marked diarrhoea so expect to spend a lot of time on the toilet!
– If you feel that the preparation has not worked well, you may take extra doses of laxative medications and please ensure you are drinking plenty of liquids. If you are uncertain, contact your doctor or the hospital where you are having the procedure done.

c) When you must stop all oral intake
– You will be advised on when you must fast, that is, when you must stop all food and drink intake, including sips of water and even chewing gum. It is important that you continue to drink clear fluids until that time, to minimise the risk of dehydration.

What are common side effects?

Your doctor will explain possible side effects with you. In general, bowel preparation is safe. However some people feel nausea, may vomit or experience abdominal cramps. If you feel thirsty or have a headache, try and drink more fluid and you may take paracetamol. Under extremely rare conditions, bowel preparation can cause kidney failure, heart failure or seizures. If you have any concerns, discuss them with your doctor.

What should I do about my regular medications?

Most regular medications can be continued throughout the bowel preparation.
If you are taking any medication that contains iron, you should stop this 1 week before the procedure.
If you are taking any blood thinning or anti-platelet medications, you should discuss with your doctor whether to continue or withhold these. Often aspirin can be continued. Usually clopidogrel (Plavix), warfarin, heparin (Clexane), rivaroxaban (Xarelto), dabigatran (Pradaxa) and apixaban (Eliquis) need to be stopped.
If you are diabetic, you should discuss with your doctor what to do about your medications. Insulin doses will need to be reduced and Forxiga, Jardiance, Steglatro, Xigduo, Jardiamet, Segluromet, Glyxambi, Qtern and Steglujan must be stopped for 36 hours prior to your test.
If you are unsure about whether you need to stop medications before your test, please clarify with your doctor well before the date.