ConditionDigestive system
Colorectal Polyps (Colon Polyps)
Colorectal 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 adenomas and sessile serrated lesions can slowly turn into colorectal cancer over about 10 years. That is why screening matters: finding and removing polyps during a colonoscopy prevents most colorectal cancers. Your follow-up schedule depends on how many polyps you had, their size and type.
Also called: Colon polyps, bowel polyps, colonic polyps, rectal polyps, adenomatous polyps
At a glance
- What they are
- Growths on the lining of the colon or rectum.
- How common
- Found in about a third or more of adults over 50 who have a screening colonoscopy.
- Types
- Adenomas and sessile serrated lesions (precancerous), hyperplastic and inflammatory polyps (usually harmless).
- Symptoms
- Usually none. Sometimes bleeding, a change in bowel habit or iron deficiency anemia.
- Treatment
- Removal during colonoscopy (polypectomy), then follow-up colonoscopy at an interval based on findings.
When to get help
See a doctor within a day or two
- Heavy rectal bleeding, black stools, or bleeding with dizziness
- Severe belly pain or fever in the days after polyp removal (possible perforation or bleeding)
Book a routine appointment
- Rectal bleeding, blood mixed in the stool, or a change in bowel habit lasting more than 3 weeks
- Iron deficiency anemia without an obvious cause
- A family history of colorectal cancer or advanced polyps in a parent or sibling, especially before age 60
- Reaching age 45 without having started colorectal cancer screening
- Pathology results after polypectomy that you do not understand
What colon polyps are
The colon and rectum are lined with cells that renew constantly. A polyp forms when a group of these cells grows abnormally into a bump. Polyps can be:
- pedunculated: on a stalk, like a mushroom
- sessile: flat or broad-based
- flat or depressed: harder to spot
They range from a few millimeters to several centimeters.
Types of colorectal polyps
| Type | Cancer potential | Notes |
|---|---|---|
| Tubular adenoma | Precancerous, low risk when small | The most common adenoma |
| Tubulovillous and villous adenoma | Higher risk | Villous features increase risk. See villous adenoma |
| Sessile serrated lesion (SSL) | Precancerous | Flat, often in the right colon, easy to miss |
| Traditional serrated adenoma | Precancerous | Uncommon |
| Hyperplastic polyp | Very low, if small and in the rectum or sigmoid colon | The most common non-adenomatous polyp |
| Inflammatory polyp | None | Seen in inflammatory bowel disease |
| Hamartomatous polyp | Low, but higher in some inherited syndromes | Juvenile polyps, Peutz-Jeghers polyps |
What makes a polyp higher risk
- size 10 mm or larger
- villous features
- high-grade dysplasia, meaning the cells look closer to cancer
- multiple adenomas, especially 5 or more
- sessile serrated lesions 10 mm or larger, or with dysplasia
These are called advanced polyps and lead to shorter follow-up intervals.
Symptoms
Most polyps cause no symptoms, which is why screening is essential. When symptoms occur:
- rectal bleeding or blood in the stool, often not visible
- iron deficiency anemia, causing tiredness and breathlessness
- change in bowel habits lasting more than a few weeks, especially with large polyps
- mucus in the stool or watery diarrhea with large villous adenomas
- belly pain, rarely, if a large polyp causes partial blockage
Causes and risk factors
- age 45 and older
- family history of colorectal cancer or advanced polyps
- inherited syndromes: Lynch syndrome, familial adenomatous polyposis, MUTYH-associated polyposis, Peutz-Jeghers syndrome
- inflammatory bowel disease affecting the colon for 8 years or more
- lifestyle: smoking, heavy alcohol use, obesity, physical inactivity, diets high in red and processed meat and low in fiber
- type 2 diabetes
- male sex
How polyps are found
Colonoscopy
A flexible camera examines the whole colon after bowel preparation. It is the only test that can both find and remove polyps in the same procedure.
Other screening tests
- FIT (fecal immunochemical test), done yearly at home, detects hidden blood
- multitarget stool DNA test (FIT-DNA), every 1 to 3 years
- CT colonography (virtual colonoscopy), every 5 years
- flexible sigmoidoscopy, examining the lower colon
Any positive non-colonoscopy test should be followed by a colonoscopy.
The US Preventive Services Task Force recommends screening for average-risk adults from 45 to 75. People with a family history usually start at 40, or 10 years before the youngest affected relative's diagnosis.
Treatment: polyp removal
- Polypectomy during colonoscopy, using a wire snare or forceps, is usually painless.
- Endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD) removes large or flat polyps.
- Surgery is needed only for polyps that cannot be removed endoscopically, or polyps containing invasive cancer with high-risk features.
All removed polyps are sent to a pathologist, who reports the type and degree of dysplasia.
Complications are uncommon: bleeding, sometimes up to 2 weeks later, and rarely perforation (a hole in the bowel wall).
Follow-up after polyps
The US Multi-Society Task Force sets surveillance intervals. Simplified examples:
| Finding | Typical next colonoscopy |
|---|---|
| Normal colonoscopy | 10 years |
| 20 or fewer small hyperplastic polyps in the rectum or sigmoid | 10 years |
| 1 to 2 tubular adenomas under 10 mm | 7 to 10 years |
| 3 to 4 tubular adenomas under 10 mm | 3 to 5 years |
| 5 to 10 adenomas under 10 mm | 3 years |
| Adenoma 10 mm or larger, villous features or high-grade dysplasia | 3 years |
| Large polyp removed in pieces (piecemeal) | 6 months |
| More than 10 adenomas | 1 year, and consider genetic testing |
Your gastroenterologist will give your specific interval based on your history and bowel preparation quality.
Prevention
- get screened from 45, or earlier if you are at higher risk
- do not smoke and limit alcohol
- stay active and maintain a healthy weight
- eat plenty of fiber, fruit, vegetables and whole grains, and limit red and processed meat
- aspirin may lower risk in some people, but it also increases bleeding, so take it for this purpose only on medical advice
Frequently asked questions
Are colon polyps cancerous?
Most are not. Adenomas and sessile serrated lesions are precancerous, meaning they can turn into cancer over many years, but only a small fraction ever do. Removing them during colonoscopy prevents that. Hyperplastic and inflammatory polyps rarely carry any cancer risk.
What causes colon polyps?
Polyps form when cells in the colon lining grow abnormally because of gene changes that build up with age. Risk rises with age, family history, inherited syndromes, inflammatory bowel disease, smoking, obesity, heavy alcohol use and diets high in red and processed meat.
Do colon polyps cause symptoms?
Usually not. Most polyps are found only by screening. Larger polyps can cause rectal bleeding, blood in the stool, a change in bowel habits or iron deficiency anemia. Any of these symptoms should be checked by a doctor.
How long does it take for a polyp to become cancer?
It usually takes about 10 years or more for an adenoma to develop into cancer, though some progress faster, especially in inherited syndromes. This slow progression is why regular screening and removal of polyps are so effective at preventing colorectal cancer.
How often do I need a colonoscopy after polyps are removed?
It depends on the number, size and type of polyps. One or two small adenomas usually mean a repeat in 7 to 10 years. Larger, numerous or high-risk polyps may need a repeat in 3 years or sooner. Your gastroenterologist will give you a specific schedule.
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 (2020)
- American Cancer Society: Understanding your pathology report, colon polyps; Colorectal cancer screening guideline
- NIDDK: Colon polyps
- US Preventive Services Task Force: Colorectal cancer screening
- MedlinePlus: Colonic polyps