Colon polyps: why they are removed and how follow-up is planned

Hearing that a polyp has been found in your bowel can be worrying, but polyps are very common, and most are harmless. Finding and removing them is one of the most effective ways to prevent bowel cancer. This guide explains what colon polyps are, why doctors remove them, what happens to them afterwards and how your follow-up is planned.

What are colon polyps?

Colon polyps, also called colorectal or bowel polyps, are small growths on the inner lining of the colon or rectum. They range from tiny bumps to larger growths and become more common with age. The exact cause is not fully understood; it is thought that the cells lining the bowel produce more cells than needed, forming a raised area.

Types of polyp

• Adenomatous polyps (adenomas) are the most common type. They include tubular and villous adenomas; villous adenomas are more likely to become cancerous.
• Hyperplastic polyps rarely become cancer.
• Serrated polyps may become cancerous over time.

Polyps that are larger, around a centimetre or more, carry a higher risk. The type of polyp can only be confirmed when it is examined in a laboratory.

Why polyps are removed

Although most polyps are not cancerous, a small number can turn into bowel cancer, usually over many years. Colorectal cancer almost always develops from polyps, so removing them before they change is a key part of prevention. The outlook is excellent when polyps are removed, whereas polyps left in place can grow and may become cancerous. For this reason, doctors usually remove any polyp they find during a colonoscopy, rather than simply watching it.

Symptoms and when to get checked

Most people with polyps have no symptoms, and many polyps are found during a colonoscopy carried out for another reason or as part of screening. Larger polyps may cause:

• blood or mucus in the stool, or bleeding from the bottom;
• a change in bowel habit, such as looser, thinner or more frequent stools;
• tiredness linked to blood loss;
• unexplained weight loss.

Blood in the stool has many possible causes, including haemorrhoids, an anal fissure, inflammatory bowel disease and some medicines, so do not try to diagnose yourself. See a doctor if you have had blood in your stool or a change in your bowel habits for around three weeks, or if you feel unusually tired or lose weight without trying. Ask for an urgent appointment if your stool is black or dark red, or if you have bloody diarrhoea. Go to an emergency department or call emergency services if bleeding will not stop or there is a lot of blood or large clots, and do not drive yourself.

Who is more likely to have polyps

Factors linked to a higher risk include:

• being over 50, as polyps become more common with age;
• a family history of bowel polyps or bowel cancer;
• inflammatory bowel disease, such as ulcerative colitis or Crohn's disease;
• being overweight;
• smoking;
• certain inherited conditions, such as familial adenomatous polyposis, Lynch syndrome and Peutz-Jeghers syndrome.

How polyps are found

Polyps can only be found through specific tests. A colonoscopy, in which a thin camera is passed through the whole large bowel, is the main test because polyps can be removed at the same time. Other options include flexible sigmoidoscopy, which examines the rectum and lower colon, CT colonography, which uses a scan with contrast, and stool tests that look for hidden blood or other changes. If a scan or stool test suggests a polyp, a colonoscopy is usually arranged to look more closely and remove it.

Stool tests are a convenient first step for many people. Depending on the test and the country, they may look for tiny amounts of blood that cannot be seen (such as the faecal immunochemical test, or FIT) or for changes in DNA shed from the bowel lining. Blood found in a stool sample can come from polyps, cancer or other conditions, so further investigation is needed to find the source.

How polyps are removed

Most polyps are removed during colonoscopy, usually with a small wire loop. The bowel lining does not feel pain, so you will not feel the removal itself. Larger or more complex polyps may need advanced endoscopic techniques, sometimes during a separate, longer procedure. Surgery to remove part of the bowel is rarely needed, but may be advised if there are very many polyps or a polyp is too large to remove safely through the colonoscope.

After removal, a little bleeding is common for a day or two. Bleeding and perforation are the main complications of colonoscopy and are more likely when polyps are removed; bleeding can occasionally be delayed by up to around two weeks. Seek urgent medical care for severe abdominal pain, fever, bleeding that does not settle, or dizziness and weakness.

What the laboratory looks for

Every polyp that is removed is sent to a laboratory, where a specialist examines it under a microscope. The report helps answer three questions:

• What type of polyp was it, and how large?
• Was it removed completely, or is there a chance it could regrow?
• Were there any precancerous or cancerous changes?

Most reports confirm a non-cancerous polyp. If cancerous changes are found, a specialist will explain what further tests or treatment may be needed.

How follow-up is planned

Your follow-up plan is based on your results rather than a fixed rule. Your gastroenterologist will consider:

• the number of polyps found;
• their size and type;
• whether they were removed in one piece and completely;
• your personal and family history and any inherited conditions.

People who have had adenomatous polyps usually need a repeat colonoscopy, with intervals ranging from about one year to ten years depending on these factors. For people without an increased risk, screening colonoscopy is generally repeated every ten years. Keep a copy of your colonoscopy and laboratory reports, especially if you are treated abroad, so that your local doctors can follow the same plan.

Lowering your risk

Some everyday habits may help reduce the risk of new polyps: eating more fibre, fruit and vegetables and less fat, keeping to a healthy weight, staying physically active, not smoking and limiting alcohol. Screening also plays an important role; in many countries it is recommended from the age of 45, and earlier or more often for people at increased risk.

Questions to ask after your colonoscopy

Your colonoscopy report and laboratory results can contain unfamiliar terms. It is reasonable to ask your gastroenterologist to go through them with you. Useful questions include:

• How many polyps were found, how large were they and what type were they?
• Were all of them removed completely, and were any removed in several pieces?
• Did the laboratory find any precancerous or cancerous changes?
• When should my next colonoscopy be, and what is that recommendation based on?
• Should my close relatives think about earlier screening because of my results?
• Which symptoms should prompt me to get in touch before my next planned check?

Writing down the answers, or asking for them in a letter, makes it easier to keep track of your follow-up over the years, particularly if you move between doctors or countries.

Next steps

If a polyp has been found, you have noticed blood in your stool or you are due for bowel screening, a gastroenterologist can explain your results and plan the right follow-up. Read more about our gastroenterology care, use Find my physician to be matched with a specialist, or see what is included in our cancer screening package.