Bowel Polyps — Types, Risks and How They’re Removed at Colonoscopy

TL;DR — A bowel polyp is a small growth on the inside lining of the large bowel. Most polyps cause no symptoms and are found incidentally at colonoscopy. The reason they matter is that some polyps — particularly adenomas — can slowly turn into bowel cancer over 5–10 years if not removed. Removing a polyp at colonoscopy prevents the cancer that would otherwise develop. Dr Goutham Sivasuthan performs polyp detection and removal (polypectomy) at the same colonoscopy procedure across Brisbane, Redland and Logan.

What is a bowel polyp?

A bowel polyp (also called a colon polyp or colorectal polyp) is a small abnormal growth that develops on the inside lining of the large bowel or rectum. Polyps vary in size from a few millimetres to several centimetres, and in shape from flat to pedunculated (on a stalk, like a small mushroom). Most polyps are benign at the time they’re found, but a subset have the potential to develop into bowel cancer over time — usually 5 to 10 years.

The two main types that matter clinically are adenomas (the precancerous type that most bowel cancers develop from) and serrated polyps (a less common but also precancerous group). Hyperplastic polyps are extremely common, generally found in the lower bowel, and carry essentially no cancer risk — but they are often removed at colonoscopy anyway because they cannot be reliably distinguished from more concerning lesions without pathology.

Types of polyps

Type	Cancer risk	Typical management
Adenoma (tubular, tubulovillous, villous)	Precancerous — risk rises with size, villous architecture, and high-grade dysplasia	Removed at colonoscopy; pathology dictates surveillance interval
Serrated polyp (sessile serrated lesion, traditional serrated adenoma)	Precancerous via the serrated pathway	Removed at colonoscopy; closer surveillance
Hyperplastic polyp	Essentially no cancer risk if small and in the rectum / lower bowel	Often removed for biopsy confirmation
Inflammatory polyp	Not premalignant; associated with IBD	Biopsy; managed in the context of the underlying inflammation
Hamartomatous polyp (e.g. juvenile, Peutz-Jeghers)	Risk depends on syndrome	Genetic assessment if part of a syndrome

Symptoms

The most important thing to know about polyps is that almost all of them are silent. They cause no symptoms whatsoever — which is exactly why bowel cancer screening exists: to find them before they make themselves known.

When polyps do cause symptoms, the most common are:

• Rectal bleeding (visible blood or microscopic blood detected on FIT testing)
• Iron-deficiency anaemia from chronic occult bleeding
• Change in bowel habit if a polyp is very large
• Mucus in the stool, especially with large villous adenomas
• Rarely, prolapse of a polyp from the rectum

Causes and risk factors

• Age — risk rises steadily from age 45 onwards
• Family history of bowel polyps or bowel cancer
• Inherited syndromes — Lynch syndrome, familial adenomatous polyposis (FAP), MUTYH-associated polyposis, serrated polyposis syndrome, Peutz-Jeghers
• Long-standing inflammatory bowel disease (ulcerative colitis, Crohn’s colitis)
• Smoking and high alcohol intake
• Obesity, low-fibre diet, processed-meat consumption
• Type 2 diabetes

How are polyps diagnosed?

Polyps are diagnosed at colonoscopy. CT colonography (sometimes called “virtual colonoscopy”) can identify polyps over 6–10 mm but cannot remove them — so a positive CT colonography is followed by a real colonoscopy. FIT (faecal immunochemical testing, used in the National Bowel Cancer Screening Program) detects microscopic blood that may come from a polyp, but a positive FIT also requires a colonoscopy for definitive diagnosis.

During colonoscopy, Dr Goutham uses high-definition imaging and image-enhanced techniques to identify polyps as small as 2–3 mm. His adenoma detection rate is published openly — every 1% increase in ADR is associated with a 3% reduction in subsequent bowel-cancer risk.

How are polyps treated?

Almost all polyps are removed in the same colonoscopy in which they’re found, a procedure called polypectomy. The technique depends on the polyp:

• Cold snare polypectomy for polyps under ~10 mm — a small wire loop removes the polyp without electrical current
• Hot snare polypectomy for larger or stalked polyps — the loop uses electrocautery to cut and seal the base
• Endoscopic mucosal resection (EMR) for larger flat polyps — a fluid cushion is injected beneath the polyp before removal
• Endoscopic submucosal dissection (ESD) for very large flat lesions — a specialised technique; some cases are referred to tertiary centres

Every removed polyp is sent for pathology. The pathology report — usually back in 7–14 days — tells you what type of polyp it was, whether it was completely removed, and dictates how soon the next colonoscopy is needed.

When to see a specialist

• A positive FIT through the NBCSP — even if you feel completely well
• Visible rectal bleeding
• New-onset iron-deficiency anaemia, especially after menopause or in men
• A first-degree relative with bowel cancer or advanced polyps (start screening 10 years earlier than the youngest affected relative)
• Known Lynch syndrome, FAP, or other inherited polyposis syndrome — surveillance from your 20s
• Personal history of polyps — surveillance per the schedule on the surveillance page

What to expect at your appointment with Dr Goutham

At your consultation, Dr Goutham will review your referral, symptoms, family history and any prior pathology. If a colonoscopy is appropriate, the practice will arrange a date, send written and digital prep instructions, and answer any prep-related questions before the day. On the day of the procedure you’ll spend 3–4 hours at the day-surgery facility; the procedure itself takes 20–40 minutes under sedation and is not felt. If any polyps are found they will usually be removed there and then. Dr Goutham explains the findings on the day with images where relevant; the formal pathology report and surveillance recommendation follow within 7–14 days, with a copy sent to your GP.

Frequently asked questions

Are bowel polyps cancer?

No — almost all polyps are benign at the time they’re found. The concern is that some types (adenomas and serrated polyps) can slowly transform into cancer over 5–10 years if left in place. Removing them at colonoscopy prevents that transformation. Less than 1 in 1,000 polyps under 1 cm contain cancer at the time of removal.

How many polyps is “normal” in a colonoscopy?

It depends on age and risk factors. In a screening colonoscopy of a healthy 50-year-old, the average chance of finding at least one adenoma is around 25–40%. Finding 1–2 small polyps is common and does not mean anything is seriously wrong. Finding numerous polyps (10+) is unusual and may suggest an underlying polyposis syndrome warranting genetic assessment.

Does polyp removal hurt?

No. Polypectomy is performed during the colonoscopy itself while you are sedated. The bowel wall has no pain receptors of the kind that respond to cutting, so the procedure is not felt. Most people have no awareness of polyps being removed at all.

What are the risks of polyp removal?

The two main risks are bleeding (most commonly within the first 7–14 days, in less than 1–2% of cases) and perforation (a tear in the bowel wall, in less than 2 per 1,000 therapeutic colonoscopies). Both are uncommon and Dr Goutham’s published complication rates are tracked annually.

How often do I need another colonoscopy after polyps are removed?

That depends on the number, size and type of polyps removed. The full risk-stratified schedule is published on the surveillance intervals page. As a rough guide: 1–2 small low-risk polyps → repeat in 5 years; multiple or advanced polyps → repeat in 3 years; piecemeal large polyp removal → repeat in 6 months to 1 year.

Can I prevent polyps from forming?

Partially. The strongest evidence-based interventions are: not smoking, moderating alcohol, maintaining a healthy weight, regular physical activity, a high-fibre diet, and reducing processed-meat intake. None of these eliminate the risk — which is why surveillance colonoscopy at the recommended interval matters even for people with a perfect lifestyle.

Book a consultation

Phone 07 3733 1551 or send a referral via the contact form. No-gap colonoscopy for insured patients across Brisbane, Redland and Logan. See about Dr Goutham, the bowel cancer screening guide, or the cost page.