In average-risk colorectal cancer (CRC) screening, colonoscopy quality is commonly assessed by the detection of sporadic adenomas and withdrawal time (WT). In inflammatory bowel disease (IBD) surveillance, however, withdrawal is more complex: even in the absence of endoscopic inflammation, endoscopists are required to perform detailed segmental IBD assessment, and obtain biopsies. Our hypothesis was that in a screening-age cohort of IBD patients without active inflammation, the yield of sporadic adenomas should be similar to that observed in non-IBD patients. We aimed to test this hypothesis in a real-world cohort, recognizing that current quality benchmarks are extrapolated from average-risk screening despite IBD patients having approximately twice the CRC risk.

We conducted a prospective observational study using a video library of colonoscopies performed at the University of Montreal Hospital Center (CHUM). All consecutive patients aged ≥45 years who underwent complete colonoscopy between 2023 and 2025 were included. Patients with endoscopic activity (Mayo score >0 or total Simple Endoscopic Score for Crohn’s Disease [SES-CD] >0), incomplete procedures, endoscopic mucosal resection, missing histopathology, or incomplete clinical data were excluded. The primary outcome was the detection of sporadic adenomas (adenoma detection rate, ADR) in IBD compared with non-IBD patients, adjusted for WT. Secondary outcomes were mean WT, polyp detection rate, adenomas per colonoscopy, polyps per colonoscopy, advanced adenoma detection rate, and sessile serrated lesion detection rate.

A total of 1421 colonoscopies were analyzed, including 155 in IBD patients and 1266 in non-IBD patients. When WT was fixed at 11.8 minutes, the proportion of colonoscopies with at least one sporadic adenoma was significantly lower in IBD than in non-IBD patients (18.5% vs. 43.4%). The gain in adenoma detection with each additional minute of WT was markedly attenuated in IBD: the odds of detecting an adenoma increased by 16.7% per additional minute in non-IBD patients compared with 2.7% per minute in IBD patients. To achieve an adenoma detection of 26%, an estimated WT of 6.8 minutes was required in non-IBD colonoscopies versus 28.3 minutes in IBD colonoscopies. In routine practice, IBD colonoscopies had a shorter mean WT than non-IBD colonoscopies (10.4 vs. 12.0 minutes).

In a screening-age cohort without endoscopic IBD activity, the detection of sporadic adenomas was substantially lower in IBD than in non-IBD patients and increased far more slowly with longer withdrawal times. These findings suggest that IBD-specific procedural demands during withdrawal, including detailed inflammatory assessment and biopsy protocols, limit the effective time available for adenoma detection. Quality thresholds derived from non-IBD screening colonoscopy may therefore not be applicable to IBD surveillance, and dedicated IBD-specific quality metrics should be developed.