How are bowel polyps diagnosed?
Most bowel (colonic) polyps do not cause symptoms. So, most people with bowel polyps will not be diagnosed. Tests may be done if you have symptoms that indicate a bowel problem, or for various other reasons. For example, if you have seen blood in your stools (faeces) or if you are found to have blood in your stools following a routine screening test which is now offered to older people.
What is a colonoscopy?
Most bowel polyps are diagnosed by this procedure. Colonoscopy is a test where an operator - a doctor or a nurse - looks into your colon. A colonoscope is a thin, flexible telescope. It is about as thick as a little finger. It is passed through the anus and into the colon. It can be pushed all the way around the colon as far as the caecum (where the small and large intestine meet). The colonoscope contains fibre-optic channels which allow light to shine down so the operator can see inside your colon.
A sample (biopsy) will be taken at the time of the colonoscopy. This is very important so that it can be checked whether the polyp is cancerous (malignant).
What about other tests?
Sometimes a bowel polyp is diagnosed by other tests:
- A special X-ray test of the bowel - this procedure is called a barium enema.
- A test procedure called sigmoidoscopy - this enables a doctor or nurse to use an instrument called a sigmoidoscope to look into the rectum and sigmoid colon. The procedure is similar to a colonoscopy but it uses a shorter telescope.
If a polyp is seen on a barium enema you will still need a colonoscopy to remove the polyp and to take a sample (biopsy) of it for further investigation.
You will also need a colonoscopy if a polyp is found when you have a sigmoidoscopy. This is to make sure there are no more polyps beyond the reach of sigmoidoscopy.
Further reading and references
Colonoscopic polypectomy and endoscopic mucosal resection: A practical guide; British Society of Gastroenterology (2008)
Guidelines for colorectal cancer screening and surveillance in moderate and high risk groups; British Society of Gastroenterology (May 2010 update from 2002)
Colonoscopic surveillance for prevention of colorectal cancer in people with ulcerative colitis, Crohn's disease or adenomas; NICE Clinical Guideline (March 2011)
Combined endoscopic and laparoscopic removal of colonic polyps; NICE Interventional Procedure Guidance, September 2014
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