This is a visual inspection of the lining of the large bowel through a flexible fibre optic telescope called a colonoscope.

Samples of tissue (biopsies) may be taken and examined under the microscope.


A strong laxative solution will be given the day before the examination in order to clear the bowel so that good views of the tissue may be obtained. Instructions on how to take this and any dietary restrictions that need to be followed will be given.

It is very important that instructions are followed carefully as a poor bowel preparation may lead to the test being abandoned so that it has to be repeated

About the test

On arrival in the department you will be asked to put on a hospital gown and sign a form giving consent to the procedure.

The examination will take place on a couch and the nurse will help you into the correct position and stay with you throughout the procedure.

The doctor will give you some sedation through a small needle in the back of the hand and once you become sleepy and relaxed, he will pass the instrument through the anus and along the bowel.

The procedure should not be painful but you may feel a little uncomfortable as air is introduced to inflate the bowel so that good views can be obtained. This may make you feel like you need to have a bowel movement but this is unlikely as the bowel has been cleared.

The examination can take as little as twenty minutes, but may be longer if there is spasm in the bowel. Your position may need to be changed to help the 'scope advance and the nurse will assist you if this is necessary.

Once the examination is finished, the 'scope is removed and you will be left to slowly recover.

After the test

You may feel a little bloated with wind pains, but these usually settle quickly.

The doctor will be able to speak to you once you are awake but if biopsies have been taken it will take a few days before a full report is available.

Are there any side effects?

There is a chance of re-sedation following the procedure so you should take the remainder of the day quietly and normal activities may resume the following day.

It is also advisable that:

1. You should not drive for twenty-four hours and you will need an escort home. (Your insurance would be invalid if you had an accident).

2. You should not operate any dangerous machinery.

3. You should not make any important decisions, (i.e. business transactions, make a Will, etc.).

4. You should not drink alcohol for twenty-four hours.

Are there any problems following colonoscopy?

There is a very small risk of damage to the bowel wall following colonoscopy resulting in bleeding or perforation. (2 in 1,000 examinations, i.e. 998 are perfectly uneventful).

If bleeding occurs this can be easily cauterised, (the passage of a small electric current to the bleeding point) or, if a perforation occurs, it will require a small operation to repair it.

A small amount of bleeding may occur following the procedure, either due to local trauma or from a biopsy site. However, if this continues for more than a few days, or if the motions become black, you should inform your doctor straight away.