Colonoscopy surveillance interval
Enter the polyps removed and see the surveillance interval the guideline sets, with the rule and its source.
No lesion at this exam — scored as a normal colonoscopy.
A colonoscopy that found no lesions is not a surveillance starting point; an average-risk patient returns to the National Bowel Cancer Screening Program.
Show exact guideline wording
Surveillance recommendations should be made after the colon has been cleared of all significant neoplasia, once histology is known and in the context of individualised assessment of benefit to the patient.
Table 3 explanatory text, p.102
Notes
- Routine average-risk screening cadence: immunochemical faecal occult blood test every 2 years, ages 45 to 74 (National Bowel Cancer Screening Program, health.gov.au).
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.
After a surveillance colonoscopy
The NHMRC tables set the interval for the next colonoscopy from the two most recent exams together, classifying each into a risk tier. A clean exam after a low-risk history returns the patient to faecal screening; age and comorbidity stopping rules apply.
The calculator gives a timeframe wherever the guideline or the screening programme sets one, and labels anything the guideline does not itself specify.
Age, stopping, and risk factors
Age. Age 75 to 80: consider surveillance only if the Charlson comorbidity score is 4 or under. Over 80, or Charlson over 4: not recommended (Table 17).
Risk factors. A family history of colorectal cancer may shorten the interval under a separate guideline.
Colonoscopy surveillance intervals: quick answers
How soon should a colonoscopy be repeated after polypectomy under Australia (NHMRC / Cancer Council)?
The National Health and Medical Research Council (NHMRC) approved Cancer Council Australia guideline sets the first interval from what was removed at the index colonoscopy. Intervals range from return to screening or 10 years for low-risk findings, through 5, 3, or 1 year, to about 6 months after piecemeal resection of a large lesion.
What is the surveillance interval for 1 to 2 small tubular adenomas under 10 mm with no high-grade dysplasia?
For 1 to 2 small tubular adenomas under 10 mm with no high-grade dysplasia, the guideline recommends colonoscopy in 10 years, and no sooner than 5 years. For 1 to 2 diminutive adenomas under 6 mm, it instead returns the patient to the National Bowel Cancer Screening Program after 4 years.
What is the surveillance interval after removing an adenoma with high-grade dysplasia or villous histology?
For 1 to 2 adenomas with high-grade dysplasia (HGD) or villous change, all under 10 mm, the guideline recommends colonoscopy in 5 years. If one of those adenomas is 10 mm or larger, the interval shortens to colonoscopy in 3 years. Size, dysplasia grade, and villous change each move the interval.
How does the number of adenomas change the surveillance interval in this guideline?
Counts drive the interval. The guideline sets colonoscopy in 5 years for 3 to 4 tubular adenomas under 10 mm without high-grade dysplasia, colonoscopy in 3 years for 5 to 9 such adenomas, and colonoscopy in 1 year for 10 or more, regardless of size or histology, with familial cancer clinic referral considered.
What is the surveillance interval for sessile serrated lesions in Australia?
The guideline counts clinically significant serrated polyps on their own pathway. For 1 to 2 sessile serrated adenomas (SSAs) under 10 mm without dysplasia, it recommends colonoscopy in 5 years. Three to four such lesions, or an SSA 10 mm or larger or with dysplasia, moves to 3 years; 5 or more moves to 1 year.
When should surveillance colonoscopy occur after piecemeal removal of a large sessile or laterally spreading lesion?
After a large sessile or laterally spreading lesion is removed piecemeal, the guideline recommends colonoscopy at about 6 months to confirm complete clearance. When the same lesion is removed en bloc, it recommends colonoscopy at about 12 months. The endoscopic resection method, not just histology, sets this interval.
Which findings return the patient to stool-test screening rather than surveillance colonoscopy?
Small hyperplastic polyps under 10 mm return the patient to usual screening; only hyperplastic polyps 10 mm or larger are surveilled. One to two diminutive adenomas under 6 mm return to the National Bowel Cancer Screening Program after 4 years, resuming the immunochemical faecal occult blood test (iFOBT) every 2 years for ages 45 to 74.
For the guideline sources and side-by-side interval tables 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.
Last reviewed against the source guidelines on 14 July 2026.
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