Colonoscopy Surveillance Calculator

Based on USMSTF 2020 post‑polypectomy surveillance guidance. Use clinical judgment and review the full report (quality, completeness, exact pathology). When multiple rules apply, this tool returns the shortest reasonable interval.

Scenario

What are you calculating?

“Second surveillance” applies when a patient already had a baseline (index) colonoscopy with findings, then had a first surveillance colonoscopy, and you’re choosing the next interval. Serrated/hyperplastic second-surveillance intervals are an evidence-limited extrapolation—confirm with full guideline text and local practice.

Exam Quality & Resection

Poor bowel prep Incomplete exam Piecemeal resection performed

Largest lesion size (mm)

Conventional Adenomas

Count Largest (mm)

Villous/tubulovillous histology High‑grade dysplasia

Serrated Lesions

SSL count SSL largest (mm) TSA count

SSL with dysplasia

Hyperplastic Polyps

HP count HP largest (mm)

Only rectosigmoid HPs <10 mm and no other polyp types

Adenomas (Second surveillance)

Baseline (index) finding category Finding at first surveillance colonoscopy

Adenoma second-surveillance intervals follow the USMSTF “second surveillance” table (baseline + first surveillance).

Serrated / Hyperplastic (Second surveillance)

Baseline (index) finding category Finding at first surveillance colonoscopy

Evidence for serrated/hyperplastic “second surveillance” is less robust; this tool extrapolates a risk-tier approach. Always confirm with the full guideline and local GI practice.

Recommended Interval

Shortest applicable interval shown. Confirm against full report & local guidelines.

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Why:

Disclaimer: Educational aid based on USMSTF 2020 post‑polypectomy surveillance. Does not replace clinical judgment. Consider family history, IBD, prior CRC, hereditary syndromes, exam quality, completeness, and exact pathology wording. For piecemeal resections, follow endoscopist recommendations for site checks.

Rule Summary (USMSTF 2020, condensed)

Normal, high‑quality colonoscopy → 10 y
1–2 tubular adenomas <10 mm → 7–10 y
3–4 tubular adenomas <10 mm → 3–5 y
5–10 adenomas → 3 y; >10 adenomas → 1 y (genetic eval)
Any adenoma ≥10 mm, villous histology, or HGD → 3 y
SSL 1–2 <10 mm → 5–10 y; SSL 3–4 <10 mm → 3–5 y; SSL 5–10 <10 mm → 3 y
SSL ≥10 mm or with dysplasia → 3 y; TSA → 3 y
Only rectosigmoid HPs <10 mm → 10 y; HP ≥10 mm → 3–5 y
Piecemeal resection of lesion ≥20 mm → site check ~6 mo
Poor prep or incomplete exam → early repeat (often ≤1 y)