Bowel polyps


Bowel polyps
Bowel polyps

Bowel polyps are small growths on the inner lining of the large intestine (colon) or rectum.  They're very common and not usually serious, but sometimes they can lead to bowel cancer.

Bowel polyps are also called colonic or colorectal polyps.

Symptoms of bowel polyps

Bowel polyps do not usually cause any symptoms, so most people with polyps will not know they have them.

They are often found during a colonoscopy, for example if you're being checked for another bowel condition, like bowel inflammation or cancer.

Rarely, larger polyps can cause symptoms such as:

  • a small amount of slime (mucus) or blood in your poo
  • bleeding from your bottom
  • a change in your normal bowel habits, such as diarrhoea or constipation
  • losing weight without trying

 Ask for an urgent GP appointment or get help from NHS 111 Wales if:

  • you've had diarrhoea for more than 7 days
  • your poo is black or dark red
  • you have bloody diarrhoea

You can call 111 or get help from 111 Wales online.

Go to A&E or call 999 if:

  • you're bleeding non-stop from your bottom
  • there's a lot of blood – for example, the toilet water turns red or you see large blood clots

Find your nearest A&E

Bowel polyps and bowel cancer

Polyps are usually harmless and do not become cancerous. But in a small number of cases a polyp can become cancerous over many years.

Bowel cancer screening can help find polyps that are more likely to develop into bowel cancer. These polyps are then removed.

Find out more about bowel cancer.

Diagnosing bowel polyps

If your GP thinks your symptoms could be caused by bowel polyps, they may recommend a colonoscopy or a CT colonography.


A colonoscopy is where a long, thin flexible tube with a small camera at the end (a colonoscope) is passed into your bottom and guided up into your bowel to look for polyps.

A colonoscopy should not be painful, but can feel uncomfortable.

CT colonography

A CT colonography scan uses X-rays and a computer to create a detailed image of your bowel and show any polyps. You'll be given special liquid before the scan so that your bowel can be seen clearly.

Cancer Research UK has more information about CT colonography

Treatment for bowel polyps

Bowel polyps are usually removed while having a colonoscopy.

A wire loop that is part of the colonoscope will cut off (snare) or burn off (cauterise) the polyp. This is called a polypectomy and is painless.

Rarely, when there are lots of polyps or a polyp is very large, surgery may be needed to remove part of the bowel.

After treatment

After the polyp or polyps have been removed, they're sent to a lab to check if:

  • the polyp has been completely removed
  • there's any risk of it regrowing
  • there's any cancerous changes in the polyp

If there are cancerous changes in the polyp, you may need further treatment. Your specialist will advise you about this.

Causes of bowel polyps

The exact cause of bowel polyps is not known. It's thought they're caused by the body producing too many cells in the lining of the bowel.

These extra cells then form into a bump, which is the polyp.

You may be more likely to develop bowel polyps if:

  • a member of your family has had bowel polyps or bowel cancer
  • you're over 50 (around 1 in 4 people over 50 will have at least 1 polyp)
  • you have inflammatory bowel disease, which includes ulcerative colitis or Crohn's disease
  • you're overweight or smoke

The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website
Last Updated: 07/09/2023 10:22:47