Three indicators are widely accepted as the most meaningful markers of colonoscopy quality. Below are Prof Kostalas' results, benchmarked against international and Australian thresholds.
Adenoma Detection Rate
The proportion of screening colonoscopies in which at least one adenoma is found. Three times the recommended benchmark of 25%, reflecting meticulous inspection technique and advanced detection methods.
Benchmark: ≥25%Caecal Intubation Rate
The proportion of colonoscopies in which the entire colon is examined — reaching the caecum. Complete examination of the colon, well above the 95% quality threshold.
Benchmark: ≥95%Sessile Serrated Lesion Detection
Detection of flat, pale precursor lesions that are commonly missed and disproportionately responsible for interval cancers. More than ten times the GESA benchmark for these commonly missed precancerous lesions.
GESA benchmark: ≥4%The most influential study linking colonoscopy quality to patient outcomes is Corley et al., New England Journal of Medicine, 2014. The investigators followed 314,872 colonoscopies performed by 136 gastroenterologists in the Kaiser Permanente system, where the adenoma detection rate (ADR) varied from 7.4% to 52.5% between individual endoscopists.
During follow-up, 712 interval colorectal cancers were identified — cancers diagnosed after a colonoscopy but before the next scheduled examination. The findings were striking:
Each 1% increase in a doctor's adenoma detection rate was associated with a 3% reduction in the patient's risk of developing colorectal cancer (hazard ratio 0.97; 95% CI 0.96–0.98).
Comparing patients of endoscopists in the highest quintile of ADR versus the lowest:
• Risk of any interval colorectal cancer was nearly halved (HR 0.52)
• Risk of advanced-stage interval cancer reduced by 57% (HR 0.43)
• Risk of death from interval cancer reduced by 62% (HR 0.38)
In other words: the endoscopist's detection rate is one of the strongest predictors of whether a colonoscopy actually protects against bowel cancer. This is why ADR is now embedded in international quality standards.
Corley DA, Jensen CD, Marks AR, Zhao WK, Lee JK, Doubeni CA, Zauber AG, et al. Adenoma detection rate and risk of colorectal cancer and death. N Engl J Med. 2014;370(14):1298–1306. doi:10.1056/NEJMoa1309086
Australian and international quality thresholds compared with Prof Kostalas' measured performance.
| Quality indicator | Recommended benchmark | Prof Kostalas |
|---|---|---|
| Adenoma Detection Rate (ADR) | ≥ 25% (screening population) | > 75% |
| Caecal Intubation Rate | ≥ 95% | > 99% |
| Sessile Serrated Lesion Detection Rate | ≥ 4% (GESA) | > 45% |
Benchmarks referenced from the Gastroenterological Society of Australia (GESA) Clinical Update for Colonoscopy, and international standards (ESGE, US Multi-Society Task Force).
Quality isn't an accident. It's the product of technique, equipment, time, and the discipline of measuring outcomes.
Meticulous inspection
Slow, deliberate withdrawal with careful evaluation of each colonic segment — including behind folds and at flexures where lesions hide.
High-definition imaging
HD endoscopes combined with virtual chromoendoscopy (NBI/BLI) enhance polyp detection and characterisation, reducing unnecessary biopsies.
Transparent measurement
Every colonoscopy is audited against national benchmarks. What gets measured gets improved — and reported back to you.
If you have been recommended a colonoscopy — or have a positive FOBT, family history of bowel cancer, or change in bowel habit — ask your GP to send a referral. Open Access Endoscopy means most patients are seen and scoped within 2–4 weeks.
Refer / Enquire About Open Access[1] Anderson JC, Rex DK, Mackenzie TA, Hisey W, Robinson CM, Butterly LF. Endoscopist adenomas-per-colonoscopy detection rates and risk for postcolonoscopy colorectal cancer: data from the New Hampshire Colonoscopy Registry. Gastrointest Endosc. 2024 May;99(5):787–795. doi:10.1016/j.gie.2023.11.014. PMID: 37993057.