A colonoscopy is a procedure to look at the lining of the back passage (rectum) and large bowel (colon). A colonoscopy provides a more accurate picture than, for an example, an X-ray.

Your doctor may recommend a colonoscopy if you have had a change in bowel habits such as persistent diarrhoea or bleeding. You may also have a colonoscopy if an inflammatory bowel disease such as ulcerative colitis or Crohn’s disease is suspected.

A colonoscopy is a relatively quick procedure and usually takes around 30 to 45 minutes to complete. During a colonoscopy, a thin, flexible tube called a colonoscope is passed through your anus to examine your rectum and large bowel. It allows your doctor to clearly see inside your rectum and colon and to take samples if necessary.

When you arrive, you will be asked to change into a hospital gown that opens at the back.

If you are being sedated for your colonoscopy, a cannula will be placed in the back of your hand which is where the sedative is administered. A sedative will make you feel a little drowsy and will also help you feel more relaxed during the procedure. You may also receive a painkiller to help you feel more comfortable too.

You will be asked to lie on your left side and your doctor will gently insert the colonoscope. Your doctor will slightly inflate your bowel with air in order to see the inside lining easier. The colonoscope is made of flexible fibres which enable it to be moved throughout your bowel by your doctor or nurse specialist. The colonoscope also has a small light and a camera on the end of it which relays images back to a monitor. You may also have samples taken from some parts of the inside of the lining of the colon which will be sent off for testing. If your doctor finds any polyps in your colon, these may be removed too.

A colonoscopy is usually performed as a day case procedure, which means there is no need for an overnight stay in hospital. Your doctor will tell you whether you need to stop taking any medications beforehand such as warfarin or ibuprofen, as these may cause complications during the procedure.

Your bowel will need to be completely empty for a colonoscopy so that your doctor can see the lining of your bowel. 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.

You will also be told to stop taking iron tablets if you do so, as these make the inside of your bowel black which makes it harder for your doctor to clearly see inside the bowel.

If you are having sedation for your colonoscopy, you must arrange for someone to collect you after your procedure as you will not be able to drive or work for a minimum of 24 hours.

Sometimes a colonoscopy is performed under general anaesthetic. This is sometimes referred to as an EUA (examination under anaesthetic). Your doctor will decide beforehand if this is necessary.

You will be given full instructions for preparation beforehand by your doctor or nurse. It is important at this stage to discuss any concerns or answer any questions you may have.

You should be able to leave within an hour after your procedure, or when the effects of the sedative have worn off. You will not be able to drive for 24 hours, and it is important someone remains with you during this period. Even if you feel that the sedative has worn off shortly after, it can stay in your blood and you may experience further drowsiness.

If you feel that you need pain relief, over the counter medicines such as paracetamol or ibuprofen can be taken.