ConditionDigestive system
Colonic Polyps (Colon Polyps)
Colonic polyps are small growths on the inner lining of the colon or rectum. They are very common after age 50 and usually cause no symptoms. Most are harmless, but some types, called adenomas and sessile serrated lesions, can slowly turn into colorectal cancer over about 10 years. Finding and removing polyps during a colonoscopy is one of the most effective ways to prevent colon cancer, which is why screening is recommended from age 45.
Also called: Colon polyps, colorectal polyps, bowel polyps, adenomas
At a glance
- What they are
- Growths that protrude from the lining of the colon or rectum.
- How common
- Found in roughly a third or more of adults screened over 50.
- Cancer risk
- Adenomas and sessile serrated lesions can become cancer; hyperplastic polyps usually do not.
- Symptoms
- Usually none. Occasionally bleeding, anemia or change in bowel habit.
- Treatment
- Removal during colonoscopy, with follow-up colonoscopy timed by the findings.
When to get help
Call 911 or go to the ER
- Passing large amounts of blood or clots from the rectum, with dizziness or fainting
See a doctor within a day or two
- Black, tarry stools
- Rectal bleeding with weight loss, persistent abdominal pain or a change in bowel habit
- Iron deficiency anemia without an obvious cause, especially over age 50 or in men
Book a routine appointment
- Any rectal bleeding, even small amounts, that has not been checked
- A change in bowel habits lasting more than 3 weeks
- Age 45 or older and not yet screened for colorectal cancer
- A family history of colon cancer or polyps, especially in a relative under 60
What colon polyps are
The colon lining constantly renews itself. Occasionally, cells grow more than they should and form a bump called a polyp. Polyps can be:
- pedunculated: on a stalk, like a mushroom
- sessile: flat or broad-based
- flat or depressed: harder to see
Size matters. Most polyps are under 1 cm. Polyps of 1 cm or more, and those with certain features under the microscope, are more likely to contain or become cancer.
Types of colon polyps
| Type | Cancer potential | Notes |
|---|---|---|
| Tubular adenoma | Low to moderate | Most common adenoma |
| Tubulovillous and villous adenoma | Higher | More likely to contain cancer, especially when large |
| Sessile serrated lesion | Moderate | Flat, often in the right colon, can be hard to see |
| Traditional serrated adenoma | Moderate | Uncommon |
| Hyperplastic polyp | Very low | Usually small, in the rectum and lower colon |
| Inflammatory polyp | None | Seen in inflammatory bowel disease |
| Hamartomatous polyp | Varies | Juvenile polyps; part of rare syndromes |
The slow sequence from normal lining to adenoma to cancer usually takes about 10 years, which gives screening time to catch polyps before they turn malignant.
Symptoms
Most polyps cause no symptoms, which is why screening matters. When symptoms occur, they may include:
- rectal bleeding or blood on or in the stool
- iron deficiency anemia from slow, hidden bleeding, causing tiredness and pale skin
- a change in bowel habit, such as constipation or diarrhea lasting more than a week
- mucus in the stool
- rarely, abdominal pain or, with large polyps, watery diarrhea
These symptoms can also be caused by hemorrhoids, diverticular disease or cancer, so they should be checked.
Risk factors
- age 45 and older
- family history of colorectal cancer or advanced polyps
- inherited syndromes: familial adenomatous polyposis (hundreds to thousands of polyps) and Lynch syndrome
- inflammatory bowel disease (ulcerative colitis or Crohn's colitis)
- lifestyle: smoking, heavy alcohol use, obesity, physical inactivity, diets high in red and processed meat and low in fiber
- type 2 diabetes
Diagnosis and screening
- Colonoscopy: a flexible camera examines the whole colon, and polyps can be removed during the same procedure. This is the gold standard.
- Stool tests: fecal immunochemical test (FIT) yearly, or multi-target stool DNA test every 1 to 3 years. A positive result needs a follow-up colonoscopy.
- CT colonography: a CT scan of the colon; polyps found need colonoscopy for removal.
- Flexible sigmoidoscopy: examines the lower colon only.
The USPSTF recommends colorectal cancer screening for adults aged 45 to 75. People with a family history or inherited syndromes often start earlier and have more frequent colonoscopies.
Treatment: polyp removal
Almost all polyps are removed during colonoscopy, a procedure called polypectomy, using a wire snare, forceps or specialized techniques for large or flat polyps. It is painless because the colon lining has no pain-sensing nerves. Risks are small and include bleeding (sometimes days later) and, rarely, perforation.
The removed polyp is sent to a pathologist, who determines its type and checks whether any cancer is present and whether the edges are clear.
Very large polyps or those that cannot be removed endoscopically may need surgery. If cancer is found, further tests and treatment for colorectal cancer follow.
Follow-up colonoscopy
How soon you need another colonoscopy depends on what was found. Guidance from the US Multi-Society Task Force includes, for example:
| Finding | Typical repeat interval |
|---|---|
| Normal colonoscopy | 10 years |
| Small hyperplastic polyps in the rectum or sigmoid | 10 years |
| 1 to 2 small tubular adenomas under 10 mm | 7 to 10 years |
| 3 to 4 small adenomas | 3 to 5 years |
| Adenoma 10 mm or larger, villous features or high-grade dysplasia | 3 years |
| Large polyp removed in pieces | About 6 months |
Your gastroenterologist will advise on your schedule.
Prevention
- attend screening from age 45
- do not smoke, and limit alcohol
- maintain a healthy weight and stay active
- eat plenty of fiber, fruit and vegetables, and less red and processed meat
Frequently asked questions
Are colon polyps cancerous?
Most are not. However, adenomas and sessile serrated lesions are precancerous and can become cancer over many years if left in place. Removing them during colonoscopy prevents this. Hyperplastic polyps usually carry very little risk.
What are the symptoms of colon polyps?
Most colon polyps cause no symptoms. Some cause rectal bleeding, blood in the stool, iron deficiency anemia or a change in bowel habits. Because symptoms are rare, screening is the main way polyps are found.
How are colon polyps removed?
They are removed during a colonoscopy using a wire loop (snare) or small forceps passed through the scope. It is usually painless and done in the same session as the diagnosis. Very large polyps occasionally need surgery.
How often do I need a colonoscopy after polyps are removed?
It depends on the number, size and type of polyps. Intervals range from about 6 months after removal of a large polyp in pieces, to 3 years for high-risk adenomas, to 7 to 10 years for 1 or 2 small adenomas.
Sources
This guide was written from current patient and clinical guidance, including:
- US Multi-Society Task Force on Colorectal Cancer: Recommendations for Follow-Up After Colonoscopy and Polypectomy
- US Preventive Services Task Force: Colorectal Cancer Screening recommendation
- American Cancer Society: Colorectal cancer screening guidelines
- NIDDK: Colon polyps
- MedlinePlus: Colonic polyps