Colon polyps

What are colon polyps?

Colon polyps are growths on the inner lining of the large bowel or rectum. Most are harmless and cause no symptoms. Some types, called adenomas, can turn into cancer over many years, so polyps are removed and tested. The NHS reports that about 1 in 4 people over 50 have at least one.

Polyps arise when the cells lining the bowel multiply more than usual. They range from tiny flat lesions to larger growths on a stalk. Adenomatous polyps carry a small cancer risk over time, while hyperplastic polyps are usually benign.

What causes colon polyps?

The exact cause of colon polyps is unknown. They form when the cells lining the bowel multiply more than usual. The risk rises with age over 50, a family history of polyps or bowel cancer, inherited polyp syndromes, inflammatory bowel disease, smoking, excess weight and a low-fibre diet.

• Ageing
• A family history of polyps or colorectal cancer
• Inherited polyp syndromes
• Low-fibre diets and lifestyle factors
• Long-standing bowel inflammation

What are the symptoms?

Colon polyps usually cause no symptoms, so most people do not know they have one. Larger polyps occasionally cause rectal bleeding, mucus, a change in bowel habit or anaemia. Because symptoms are rare, screening from age 50 is how most polyps are found.

• Usually no symptoms
• Occasional minor bleeding
• Mucus or altered bowel habits with large polyps
• Anaemia in rare cases

When should I see a colorectal surgeon?

See a doctor for blood in the stool, a lasting change in bowel habit, unexplained weight loss or a lot of mucus, which colon polyps can cause. Begin screening at age 50, or earlier with a family history. Seek urgent care for black or dark red stools or heavy rectal bleeding.

The warning signs below need prompt attention.

• Blood in the stool
• A family history of many polyps
• Weight loss or changed bowel habits
• A large or suspicious polyp

How is it diagnosed?

Colon polyps are found by colonoscopy, which examines the whole large bowel and allows polyps to be removed in the same session. Removed polyps are sent to a laboratory to identify their type. CT colonography is an alternative scan, and genetic assessment is arranged when an inherited syndrome is suspected.

• Colonoscopy to find and remove polyps
• Biopsy and laboratory examination
• CT colonography in some cases
• Genetic assessment for inherited syndromes

How are colon polyps treated?

Most colon polyps are removed during colonoscopy with a wire loop, a procedure called polypectomy. Rarely, a very large or high-risk polyp that cannot be removed safely needs surgery to remove part of the bowel. Surveillance colonoscopy at set intervals follows, based on the type and number of polyps.

• Removal during colonoscopy (polypectomy)
• Surgery for very large or high-risk polyps
• Surveillance colonoscopy at set intervals
• Screening of relatives when an inherited condition is found

What are the risks and complications?

Polyp removal carries a small risk of bleeding afterwards and a rare risk of bowel injury. A small polyp can be missed, and new polyps develop in at least 30 percent of people who have had them, which is why surveillance matters. A polyp that cannot be removed safely needs surgery.

• Bleeding after removal
• Rare bowel injury
• A small polyp being missed
• Need for surgery if a polyp cannot be removed safely