What is a colonoscopy?
A colonoscopy is a way of looking at the inside of your bowel. A doctor or nurse passes a thin flexible tube (colonoscope) into your back passage. The tube has a tiny light and camera on the end to show any abnormal areas. A colonoscopy can also see whether there are any small growths (polyps) in the lining of the bowel. It is one of the main tests used to diagnose bowel cancer. The procedure is usually done in the hospital's endoscopy department and takes about 30 minutes.
During the colonoscopy, photographs and samples (biopsies) of the cells on the inside of the large bowel can be taken. If polyps are seen these can often be painlessly removed using a wire loop that is passed down the colonoscope.
Preparing for a colonoscopy
The bowel has to be completely empty for a colonoscopy. You will be given some information about what you need to do which will involve:
- Following a careful diet for a few days before your test.
- Taking laxatives, which the hospital will give you with instructions about when to take them.
Having your colonoscopy
Shortly before the colonoscopy, you may be given a sedative to help you feel relaxed.
Once you are lying comfortably on your side, the nurse or doctor will gently pass the colonoscope into your back passage. The tube is flexible so it can easily pass around the curves of the bowel.
Having a colonoscopy can be uncomfortable. If you do have pain, it is usuall mild. If you find it very painful, tell the doctor or nurse straight away. They may give you Entonox which is a gas that can relieve pain. It is sometimes called gas and air. You breathe it in through a mouthpiece.
Sometimes it is not possible to see the whole bowel during a colonoscopy. This can happen if the bowel is not completely empty or if the colonoscope can't pass around a bend in the bowel to reach the end. If this happens, you may be asked to have another colonoscopy or a CT Colonography.
After a colonoscopy
Most people are ready to go home a couple hours after their test.
If you have had a sedative:
- You will need someone to collect you from the hospital.
- You should have someone with you for 24 hours.
- You should not drive for 24 hours afterwards.
If you only had Entonox you should be able to drive home when the nurses say you have recovered. You will not need someone to stay with you overnight.
It is rare to have any serious problems after the test. Contact your GP or go to your nearest emergency department (A&E) straight away if you:
- Have severe tummy pain.
- Have a high temperature.
- Being sick.
- Bleeding from the back passage.
Risks of a colonoscopy
Most people who have a colonoscopy have no problems, but rarely there can be problems.
- A small number of people have heavy bleeding after having a polyp removed or a biopsy. This can usually be treated quickly during the test. However, some people may need to be admitted to hospital to have this treated.
- Rarely, the bowel can be torn or damaged. If this happens, you will usually need an operation to repair the tear.
All the risks of a colonoscopy will discussed with your doctor as part of the consent process.
