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.

The cleaner the bowel, the safer and more accurate the procedure.

How is bowel preparation undertaken?

Your doctor will give you specific information about what preparation will be best for you. This will include information about

  • a) How to modify your diet
    – You may need to reduce your fibre intake for a couple of days before the procedure.
    – You will be asked to have a “clear fluid diet” for around a day before the procedure. This means you can have no solid food and no cloudy drinks. Clear fluids are those 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) When to take the bowel preparation medication (laxatives)
    – You will be advised on what medications 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 diarrhea so expect to spend a lot of time on the toilet!
  • 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 blood thinning medications, you should discuss with your doctor whether to continue or withhold these. For example, aspirin, clopidogrel (Plavix), warfarin, heparin (Clexane), rivaroxaban (Xarelto), dabigatran (Pradaxa), apixaban (Eliquis).

If you are diabetic, you should discuss with your doctor what to do about your medications, particularly if you are using insulin.

If you are taking any medication that contains iron, you will usually need to stop this 1 week before the procedure.

Good Bowel Preparation
Poor Bowel Preparation