For your doctor to see the lining of your colon clearly, it needs to be completely empty. To achieve this, you will need to follow a special diet for a few days before the procedure and you will be asked not to eat any solids on the day before your examination. You will also be given a laxative, which will come with detailed instructions on how and when to take it.
If you are having sedation, this may be given through a small plastic tube (cannula) placed in a vein in the back of your hand. You may need oxygen through a mask during the procedure and for a short time afterwards.
With you resting on your side, your doctor will examine your back passage with a finger before carefully inserting the colonoscope. Lubricating jelly will be used to make this as easy as possible.
Air will be passed through the tube and into the colon to make the lining easier to see. When this happens, you may briefly feel pains similar to trapped wind. You may also feel that you want to go to the toilet, but as the colon is empty, this will not be possible. You may pass wind, but try not to feel embarrassed, as the staff expect this to happen.
At the end of the colonoscope, a tiny light and lens allow your doctor to see the lining of the colon. The lining is examined by looking directly through the colonoscope, or at pictures it sends to a video screen.
During the procedure, you may be asked to change your position – for example turning from your side onto your back. This helps your doctor to examine different areas of the colon with the colonoscope more easily. If necessary, a small biopsy will be taken for analysis. Any polyps that are found can also be removed. This is done using special instruments passed inside the colonoscope, and is quick and painless.
Afterwards, the colonoscope is removed quickly and easily. The procedure takes about 20 to 30 minutes to perform and may be a bit uncomfortable.
After the examination, you may feel bloated and have wind pains, but these usually clear up quite quickly. The sedative may make you feel sleepy. If a biopsy has been taken or a polyp has been removed, you may experience a small amount of bleeding from your back passage after the procedure.