A colonoscopy is a routine test to examine the lining of your bowel, also called the large intestine or colon. This is done using an endoscope, which is a flexible tube, about the thickness of a (little) finger, which has a camera and light at one end. It is passed through the anus (back passage) and carefully moved around the large bowel.
The colonoscopy allows an examination of the entire colon (1200–1500 mm in length) and can provide a visual diagnosis (e.g. ulceration, polyps) as well as giving opportunity for biopsy or removal of suspected colorectal cancer lesions. Colonoscopy can remove polyps as small as one millimetre or less. Once polyps are removed, they can be studied with the aid of a microscope to determine if they are precancerous or not. It can take up to 15 years for a polyp to turn cancerous.
You may have been advised to have a colonoscopy if you have:
- bleeding from your anus
- pain in the lower abdomen (tummy)
- persistent diarrhoea
- changes in your bowel habits
- a strong family history of bowel cancer
- been placed on a bowel cancer screening pathway
- have an existing condition that needs reviewing such as Crohn’s disease or colitis.