Colonoscopy surveillance interval
Enter the polyps removed and see the surveillance interval the guideline sets, with the rule and its source.
Not for intervals after a surveillance colonoscopy.
Tick if any apply.
| Prevalence | Histopathology | Guideline interval |
|---|---|---|
| ~45–60% | Tubular adenoma | 10 years |
| ~20–30% | Hyperplastic | No surveillance required |
| ~5–15% | Tubulovillous / villous | 5 years |
| ~1–8% | Sessile serrated | 5 years |
| <1% | Traditional serrated | 3 years |
How NHMRC / Cancer Council sets the colonoscopy surveillance interval
The National Health and Medical Research Council (NHMRC) approved Cancer Council Australia guideline sets the first surveillance colonoscopy interval from what was found and completely removed at the index exam. It handles conventional adenomas and clinically significant serrated polyps as separate pathways, then assigns an interval from the number of lesions, their size (a 10 mm cut-off), and whether there is high-grade dysplasia or villous change. Low-risk findings go back to the National Bowel Cancer Screening Program (NBCSP), higher-risk findings are booked at 5, 3, or 1 year, and lesions taken out piecemeal are rechecked at around 6 months.
| Finding at the baseline colonoscopy | Surveillance interval |
|---|---|
| 1 to 2 diminutive (under 6 mm) tubular adenomas, low-risk | Return to the National Bowel Cancer Screening Program after 4 years |
| 1 to 2 small (under 10 mm) tubular adenomas, no high-grade dysplasia | 10 years, colonoscopy (no sooner than 5 years) |
| 1 to 2 adenomas with high-grade dysplasia or villous change, all under 10 mm; or 3 to 4 tubular adenomas without high-grade dysplasia, all under 10 mm | 5 years, colonoscopy |
| 1 to 2 adenomas with high-grade dysplasia or villous change where one is 10 mm or larger; or 3 to 4 tubular adenomas where one is 10 mm or larger; or 3 to 4 adenomas with villous change and/or high-grade dysplasia, all under 10 mm | 3 years, colonoscopy |
| 5 to 9 adenomas | 3 years if all are tubular, under 10 mm, and without high-grade dysplasia; otherwise 1 year |
| 10 or more adenomas (consider referral to a familial cancer clinic) | 1 year, colonoscopy, regardless of size or histology |
| 1 to 2 sessile serrated adenomas, all under 10 mm, no dysplasia | 5 years, colonoscopy |
| 3 to 4 sessile serrated adenomas under 10 mm without dysplasia; or 1 to 2 sessile serrated adenomas 10 mm or larger or with dysplasia; or a hyperplastic polyp 10 mm or larger; or 1 to 2 traditional serrated adenomas of any size | 3 years, colonoscopy |
| 5 or more sessile serrated adenomas under 10 mm without dysplasia; or 3 to 4 sessile serrated adenomas 10 mm or larger or with dysplasia; or 3 to 4 traditional serrated adenomas of any size | 1 year, colonoscopy |
| Hyperplastic polyps under 10 mm | Usual screening (only hyperplastic polyps 10 mm or larger are surveilled) |
| Large sessile or laterally spreading lesion removed piecemeal | About 6 months, colonoscopy |
| Large sessile or laterally spreading lesion removed en bloc | About 12 months, colonoscopy |
Australia runs conventional adenomas and clinically significant serrated polyps as separate counting pathways, giving serrated lesions their own 5, 3, and 1 year intervals rather than folding them into the adenoma rules.
Source: Cancer Council Australia / NHMRC — Clinical practice guidelines for colorectal cancer: Colonoscopy surveillance ↗. This is the baseline colonoscopy table; enter specific findings in the calculator above for the rule and its exact wording.
For common questions and the source behind each rule across all the guidelines, see the colonoscopy surveillance guideline reference.
Reference tool for health professionals. Not medical advice, not a medical device, and does not make or replace a clinical decision. The calculation runs in your browser; the findings you enter are not transmitted or stored. The Aescia clinical team reviews this tool periodically against the source guidelines and updates it when they change, but guidelines are revised without notice; verify against the current version before acting. If you notice an error, tell us at contact@aesciahealth.com.
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