A polyp is a small growth on the lining of the bowel. Most are harmless, but some types can slowly turn into cancer over many years. Removing them at colonoscopy is one of the most effective ways to prevent bowel cancer. Whether you need another colonoscopy, and when, depends on the number, size and type of polyps found.

What is a polyp?

A polyp is a growth on the inner lining of the bowel; some are flat rather than raised. Polyps are very common after age 50 and usually cause no symptoms. Only a small proportion would ever become cancer, usually over many years, which is why finding and removing them works so well.

Types of polyp

After removal, the polyp is examined under the microscope (histology). Your report may mention:

• Adenoma: the most common precancerous polyp. Words such as tubular, tubulovillous or villous describe its structure
• Dysplasia: abnormal-looking cells. Low-grade dysplasia is usual in adenomas. High-grade dysplasia is a more advanced change, but it is still not cancer
• Serrated polyps: a group that includes sessile serrated lesions, which can also become cancer, especially when larger
• Hyperplastic polyps: common, usually small polyps in the lower bowel that carry very little risk
• Other types, such as inflammatory polyps in people with colitis, which are not precancerous

How polyps are removed

Most polyps are removed painlessly during colonoscopy with a small wire loop (snare) or forceps. Larger or flat polyps may need a specialised technique, sometimes in pieces or at a separate procedure. Uncommon risks include bleeding, which can occur up to two weeks later, and, rarely, a tear (perforation). If you take blood thinners, your team will advise you beforehand.

When is the next check?

British, European and American guidelines differ in detail, but share one principle: the more numerous, larger or more advanced the polyps, the sooner the next check. General examples:

• One or two small tubular adenomas (under 10 mm) with low-grade dysplasia: an early repeat is usually not needed. You may return to the routine bowel cancer screening offered where you live, or have a repeat colonoscopy after several years (American guidance suggests 7 to 10 years)
• Small hyperplastic polyps in the rectum or lower colon: no extra follow-up beyond routine screening
• An adenoma or serrated polyp 10 mm or larger, a serrated polyp with dysplasia, high-grade dysplasia, or several adenomas (often five or more): a repeat colonoscopy is often advised after about 3 years, depending on the exact combination and the guideline your team follows
• A large polyp (usually 20 mm or more) removed in pieces: an early check of the site, usually within about 6 months, to make sure it was removed completely, followed by a further check about a year later
• Cancer found within a polyp: you will be referred for further assessment

These are examples only. Your plan also depends on the bowel preparation, whether all polyps were removed, your age, health and family history. Your doctor will advise the plan that applies to you.

What it means for your family

Small polyps do not usually change advice for your relatives. Your parents, brothers, sisters and children may need earlier screening if:

• You were found to have an advanced polyp or bowel cancer, especially at a younger age
• You have had many adenomas over time (for example, 10 or more), which may suggest an inherited condition and lead to a referral for genetic assessment
• Bowel cancer or polyps already run in your family

Your doctor will tell you if your results mean your family should be checked.

Reducing your risk

• Keep your follow-up appointments, and report new symptoms between checks
• Eat plenty of fibre, limit red meat and avoid processed meat
• Stay active and keep a healthy weight
• Do not smoke

Common questions

This leaflet is general information and does not replace advice from your own doctor. Version 1.0, October 2026. Next review October 2028.