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Health condition

Colon polyps, why they matter, and how modern endoscopy handles them.

Most polyps never cause trouble. Some quietly turn into colorectal cancer. Screening finds them early, and colonoscopy removes almost all of them in a single visit.

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A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Editorial team

    Written by our editorial team from the UK sources listed on each page.

  • 02

    Sourced from guidance

    Checked against BSG, ESGE, NICE and Bowel Cancer UK sources you can see at the end.

  • 03

    Current for 2026

    Reflects BSG post-polypectomy surveillance, NHS BCSP FIT screening and modern endoscopic resection.

Key facts

Colon polyps at a glance.

The essentials in plain English - what they are, which types matter, and how they’re removed and followed up in the UK today.

  • What they are

    Mucosal growths in the colon or rectum. Most are benign, but some adenomas and serrated lesions can progress to colorectal cancer.

  • Main types

    Adenomatous (tubular, villous, tubulovillous), serrated (hyperplastic, sessile serrated, traditional serrated), hamartomatous and inflammatory.

  • Adenoma risk

    Villous adenomas carry the highest cancer risk (around 25% can become cancerous). Tubular adenomas are the most common and lowest risk.

  • How they are found

    Usually asymptomatic. Detected through the NHS Bowel Cancer Screening Programme (FIT) or symptomatic colonoscopy.

  • Treatment

    Endoscopic polypectomy at colonoscopy is standard. Cold snare, hot snare, EMR or ESD depending on size and morphology.

  • Syndromes

    FAP, MUTYH-associated polyposis, Lynch syndrome, serrated polyposis, Peutz-Jeghers, juvenile polyposis and Cowden need specialist genetics.

Why this guide matters

A treatable precursor - not a diagnosis to fear.

Colorectal cancer usually starts as a polyp that takes years to develop. Screening and clean endoscopic removal is the single most effective way to prevent it.

  • Not all polyps are the same

    Tubular adenomas are the most common and lowest risk. Villous adenomas and sessile serrated lesions carry the highest risk of progression.

  • Screening finds them early

    The NHS Bowel Cancer Screening Programme uses FIT to trigger colonoscopy - catching polyps years before they become cancer.

  • Removal breaks the sequence

    Polypectomy at colonoscopy interrupts the adenoma-carcinoma sequence and prevents most colorectal cancers.

How the diagnosis is made

From screening test to a clear plan.

The steps a UK GP, screening service or gastroenterologist will normally follow - so you know what to expect and why.

  1. 01

    Assessing

    Symptom and family history

    A careful history covering bleeding, bowel habit change, iron-deficiency anaemia and any family history of polyps, colorectal or Lynch-associated cancers.

  2. 02

    Assessing

    FIT and BCSP screening

    The NHS Bowel Cancer Screening Programme offers FIT every two years from age 60 to 74 (expanding to age 50). A positive FIT triggers colonoscopy.

  3. 03

    Assessing

    Symptomatic 2WW pathway

    Symptomatic patients enter the two-week wait suspected cancer pathway, often with a FIT-symptomatic result to guide urgency.

  4. 04

    Confirming

    Colonoscopy - the gold standard

    Full colonoscopy allows visualisation, biopsy and same-session polypectomy. CT colonography is an alternative when colonoscopy is not possible.

  5. 05

    Confirming

    Histology and risk stratification

    Every removed polyp is examined for type, dysplasia grade, carcinoma in situ and, for malignant polyps, Haggitt or Kikuchi levels of invasion.

  6. 06

    Preparing

    Genetic assessment when suggested

    A polyposis panel (APC, MUTYH, MMR genes, STK11, SMAD4, BMPR1A, PTEN, POLE, POLD1) and cascade family testing where a syndrome is suspected.

  7. 07

    Preparing

    BSG surveillance plan

    A tailored follow-up interval - 1, 3 or 5 years - based on polyp number, size, histology and syndrome status per BSG guidelines.

Typical timeline: from a positive FIT to a settled surveillance plan in weeks.

Symptoms

What colon polyps actually feel like.

Most people have no symptoms at all. When symptoms occur, the polyp is usually large - and it’s time to move quickly.

  • Usually silent

    Most polyps cause no symptoms and are picked up during screening or investigation of another problem.

  • Rectal bleeding

    Fresh red or dark blood mixed with stool can occur, especially with larger or distal polyps.

  • Iron-deficiency anaemia

    Slow, chronic blood loss from a right-sided polyp can present as unexplained iron-deficiency anaemia.

  • Change in bowel habit

    A large polyp may cause new looser stools, constipation or a feeling of incomplete emptying.

  • Mucus discharge

    Villous adenomas can produce noticeable mucus, occasionally with electrolyte disturbance if very large.

  • Prolapse or intussusception

    Very large pedunculated polyps rarely prolapse through the anus or cause intussusception.

  • Positive FIT

    A positive faecal immunochemical test is the most common trigger for colonoscopy and polyp detection.

  • Red flag - suspected cancer

    Weight loss, persistent bleeding, anaemia or an abdominal mass warrants urgent two-week wait referral.

Treatment

How colon polyps are managed in the UK.

The vast majority are removed at colonoscopy. Surgery, genetics-led surveillance and lifestyle change fill in the gaps for higher-risk patients.

  • Cold snare polypectomy

    The default for diminutive and small polyps under 10 mm. Safe, effective and low risk of bleeding or perforation.

  • Hot snare polypectomy

    Used for larger or pedunculated polyps, with diathermy to seal the stalk and reduce bleeding.

  • Endoscopic mucosal resection (EMR)

    For large, flat or sessile polyps. A submucosal lift and snare resection performed by an experienced endoscopist.

  • Endoscopic submucosal dissection

    ESD is reserved for high-risk or complex lesions in tertiary centres, allowing en-bloc resection with clear margins.

  • Endoscopic full-thickness resection

    EFTR is selective and used for difficult lesions such as those at diverticula or recurrent polyps.

  • Surgical colectomy

    Reserved for malignant polyps with deep invasion, large sessile lesions not amenable to endoscopy, or polyposis syndromes.

  • Aspirin chemoprophylaxis

    Evidence from the CAPP2 trial supports aspirin for CRC prevention in Lynch syndrome. Emerging evidence in the general population.

  • Lifestyle modification

    Higher fibre, less processed and red meat, less alcohol, weight management, exercise and smoking cessation all reduce risk.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP or gastroenterologist knows your history and colonoscopy findings and can tell you which parts apply to you. If in doubt, get seen.

  • British Society of Gastroenterology (BSG). Post-polypectomy and post-colorectal cancer resection surveillance guidelines.

  • European Society of Gastrointestinal Endoscopy (ESGE). Colorectal polypectomy and EMR guidelines.

  • NICE. Colorectal cancer: diagnosis and management (NG151) and suspected cancer recognition and referral (NG12).

  • NHS Bowel Cancer Screening Programme (BCSP) and Bowel Cancer UK patient guidance.

Red flags

When polyps need urgent attention.

Most colonoscopies and polypectomies are straightforward. These are the situations that need specialist input or fast escalation.

  • Malignant polyp on histology

    A polyp containing invasive cancer needs MDT discussion. Endoscopic clearance may be adequate, or completion surgery may be required.

  • Unresectable large sessile polyp

    A polyp that cannot be safely removed endoscopically may need surgical resection, ideally at a specialist centre.

  • Suspected polyposis syndrome

    Multiple polyps, young age, strong family history or extra-colonic features (e.g. mucocutaneous pigmentation) should prompt urgent genetics referral.

  • Post-polypectomy bleeding

    Fresh bleeding after polypectomy may need repeat colonoscopy. Delayed bleeds can occur up to two weeks afterwards.

  • Post-polypectomy perforation

    Severe abdominal pain, fever or peritonism after colonoscopy needs immediate hospital assessment.

  • Two-week wait symptoms

    Weight loss, persistent rectal bleeding, iron-deficiency anaemia or an abdominal mass warrant urgent suspected-cancer referral.

  • FAP with near-100% cancer risk

    Familial adenomatous polyposis carries near-certain colorectal cancer without prophylactic colectomy. Upper GI and desmoid surveillance also needed.

  • Lynch syndrome and rapid progression

    Fewer polyps but rapid adenoma-carcinoma progression. Requires 1 to 2-yearly colonoscopy from age 25 to 30 and wider surveillance.

  • Juvenile polyposis complications

    Multiple juvenile polyps can bleed, prolapse or cause intussusception, and carry increased colorectal cancer risk.

Living with it

A preventable cancer, with the right follow-up.

Four things that make the biggest difference - screening, diet, lifestyle and sharing what you know with your family.

A quiet reminder

Small, boring habits prevent big diagnoses.

Returning the FIT kit, attending the surveillance colonoscopy, and eating well for decades is what makes colorectal cancer one of the more preventable cancers.

  1. 01 Screen

    Keep up with FIT and surveillance

    Return your NHS bowel screening kit and attend surveillance colonoscopy on the interval your gastroenterologist has set.

  2. 02 Diet

    Eat for your colon

    A high-fibre Mediterranean-style diet with less processed and red meat is associated with lower polyp and cancer risk.

  3. 03 Lifestyle

    Move, moderate, don’t smoke

    Regular activity, a healthy weight, low alcohol intake and stopping smoking all reduce colorectal cancer risk.

  4. 04 Family

    Share the family history

    If you have a syndrome or a strong family history, cascade genetic testing can guide screening for relatives.

Frequently asked

Everything we get asked about colon polyps.

Quick answers on types, screening, polypectomy, surveillance and family history.

  • What are colon polyps?

    Colon polyps are mucosal growths in the lining of the large bowel or rectum. Most are benign, but adenomatous and some serrated polyps can slowly progress to colorectal cancer through the adenoma-carcinoma sequence.

  • Which polyps become cancer?

    Adenomatous polyps - especially villous and tubulovillous types - and sessile serrated lesions are the main precursors. Advanced adenomas (over 10 mm, villous, or with high-grade dysplasia) carry the highest risk. Hyperplastic distal polyps under 10 mm are generally benign.

  • How are polyps found?

    Most are picked up during the NHS Bowel Cancer Screening Programme after a positive FIT, or during colonoscopy for symptoms such as bleeding, anaemia or a change in bowel habit. CT colonography is an alternative when colonoscopy is not possible.

  • How are polyps removed?

    Nearly all are removed at colonoscopy. Cold snare is used for small polyps, hot snare for larger or pedunculated lesions, and endoscopic mucosal resection or submucosal dissection for large, flat or high-risk polyps. Surgery is only needed for a minority.

  • When do I need surveillance colonoscopy?

    The BSG bases surveillance on polyp features. As a guide, 3 years for an adenoma of 10 mm or more, high-grade dysplasia, five or more adenomas or villous change; 5 years for one to four small (under 10 mm) adenomas; and no surveillance for small distal hyperplastic polyps.

  • What if there is a strong family history?

    A strong family history, a young diagnosis or multiple polyps may point to a syndrome such as FAP, Lynch, MUTYH-associated polyposis, Peutz-Jeghers, juvenile polyposis or Cowden. Referral to clinical genetics for a polyposis panel and cascade family testing is important.

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