Polyp Surveillance After Colonoscopy

After a colonoscopy, you’ll often see in the report:

👉 “Repeat colonoscopy in 3 years”
👉 “Back to screening”
👉 “Site check in 3 months”

As the ward/clinic doctor, you should understand why.

Polyp surveillance is about:

Identifying who is high risk for colorectal cancer
and avoiding unnecessary repeat scopes in low-risk patients

Most patients do NOT need frequent colonoscopies.

This guide focuses on simple, practical NHS decision-making, not memorising complex tables.

✅ First principle

Always ask:

Is this patient high risk or low risk?

Because:

  • High risk → surveillance colonoscopy
  • Low risk → no routine scope, return to screening

That’s the key decision.

✅ Step 1 – Understand what counts as “higher risk” polyps

Not all polyps are equal.

Some matter more.

Polyps that matter more clinically:

Larger size

  • ≥10 mm

Dysplasia

  • High-grade dysplasia

Multiple polyps

  • Several adenomas

Serrated polyps with dysplasia

These increase cancer risk → need closer follow-up.

✅ Step 2 – Who needs surveillance colonoscopy?

Think practically.

🔴 HIGH RISK → repeat colonoscopy at 3 years

If:

Either:

  • ≥2 premalignant polyps AND at least one is advanced

OR

  • ≥5 premalignant polyps total

Examples you’ll see:

  • 3 adenomas, one 12 mm
  • 6 small adenomas
  • Large serrated polyp with dysplasia

👉 These patients need 3-year surveillance colonoscopy

🟢 LOW RISK → no routine colonoscopy

If:

  • 1–2 small (<10 mm) adenomas
  • Only tiny hyperplastic polyps
  • Nothing concerning histologically

👉 No surveillance needed
👉 Return to national bowel screening programme

Most patients fall into this group.

Do not over-scope.

✅ Step 3 – Special situation: “site check” (very commonly confused)

This is NOT surveillance.

It’s just checking that a large polyp was completely removed.

When to do a site check?

If:

  • Large polyp removed piecemeal
  • Incomplete resection suspected
  • Large EMR/ES D
  • Dysplasia with uncertain margins

👉 Repeat scope in 2–6 months

Purpose:
Confirm clearance

Then:
Follow normal surveillance schedule

✅ Step 4 – Age and fitness matter

Very important clinically.

Ask:

Will this patient actually benefit from surveillance?

If:

  • Frail
  • Limited life expectancy
  • Elderly (>75–80)

Often:
👉 surveillance not helpful

Colonoscopy has risks.

Don’t scope automatically.

Individualise.

✅ Practical ward thinking (real-life scenarios)

Scenario 1

Two 5 mm adenomas removed
→ low risk
→ no surveillance

Scenario 2

Three adenomas, one 15 mm
→ high risk
→ repeat colonoscopy in 3 years

Scenario 3

Large 25 mm polyp removed piecemeal
→ site check at 3–6 months first
→ then routine surveillance plan

Scenario 4

80-year-old with multiple comorbidities
→ surveillance often not appropriate
→ discuss risks vs benefits

✅ What juniors should actually do

When reading a colonoscopy report:

Check:

  • Number of polyps
  • Size
  • Histology
  • Was removal complete?
  • Plan documented?

If unclear → discuss with gastro/dietitian/endoscopy team.

Don’t guess.

❌ Common junior mistakes

  • Repeating colonoscopy too often
  • Treating small low-risk adenomas aggressively
  • Forgetting site check after piecemeal resection
  • Ignoring age/frailty
  • Copy-pasting “3-year scope” for everyone

Most patients don’t need surveillance.

✅ Simple rule to remember

Think:

  • Few small polyps → no scope
  • Many or large or dysplastic → 3 years
  • Piecemeal removal → early site check

That covers 95% of decisions.

✅ Take-home concept

Surveillance is for higher-risk polyps only.
Don’t over-scope low-risk patients.
Use 3 years for high risk, and early site checks for incomplete resections.