Colonic (Bowel) Polyps


A colonic (bowel) polyp is a small benign (noncancerous) growth that sometimes forms on the inside lining of the colon or rectum. Some people develop just one colonic polyp, but it is not uncommon to develop two or more. A colonic polyp may have a stalk and a head which looks like a small mushroom growing from the lining of the bowel. Some are flatter and just look like a lump on the lining of the bowel.

Types of colonic polyp

Colonic polyps are generally divided into three types: hyperplastic polyps, adenomas, and polyposis syndromes.

  1. Hyperplastic polyps
  2. These are common, small - usually less than half a centimetre in diameter. They are generally regarded as harmless, perhaps very rarely developing into a cancer.

  3. Adenomas
  4. These too are common. Most are small, usually less than one centimetre in diameter, but sometimes they are bigger. Most colorectal cancers (bowel cancers) develop from a polyp that has been present for 5-15 years.

  5. Polyposis syndromes
  6. Polyposis syndromes are a group of hereditary conditions. They include: familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (HNPCC)/Lynch's syndrome, Gardner syndrome, Turcot's syndrome, Peutz-Jeghers syndrome, Cowden's disease, familial juvenile polyposis, and hyperplastic polyposis. These are rare syndromes, occur in young people, and often cause multiple colonic polyps that have a high chance of developing into bowel cancer.

Who gets bowel polyps and what causes them?

Most colonic polyps develop in older people. The cause is not clear. The polyp is like a local fleshy overgrowth of tissue that lines the bowel. What causes this overgrowth to happen is not clear.

What are the symptoms of colonic polyps in older people?

Most people with one or more colonic polyps do not have any symptoms. Occasionally, symptoms may occur. These include: bleeding from the anus, mucus mixed in with faeces, and, rarely, diarrhoea or constipation.

How are colonic polyps diagnosed?
  • Colonoscopy
  • Colonoscopy is a test where an operator 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 round 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.

  • Other tests
  • Sometimes a colonic polyp is diagnosed by other tests such as a barium enema (a special X-ray test of the bowel) or sigmoidoscopy (like colonoscopy, but using a shorter telescope).

How are colonic polyps treated?

If you are diagnosed with a colonic polyp, you will usually be advised to have it removed, even if it is causing no symptoms. This is to prevent the (small) risk of it developing into a cancer at some point in the future.

Most colonic polyps can be removed during a colonoscopy (described earlier). The colonoscope has a side channel down which grabbing devices can pass. These can be manipulated by the operator.

Your doctor will advise on the need for follow-up. This may depend on factors such as the size of the polyp, the exact subtype and laboratory report, and your age.

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