Post written by Ahmir Ahmad, MRCP, from the Wolfson Unit for Endoscopy, St Mark’s Hospital, Harrow, London, UK.

Real-time optical diagnosis (OD) is now possible because of image-enhancing technologies offering the potential for huge cost and time savings associated with histopathology. 

Despite several GI societies endorsing a “resect and discard” strategy for low-risk diminutive polyps, there has not been widespread adoption. 

In the DISCARD3 study, we evaluated the OD learning curve and feasibility of a resect and discard strategy for ≤5-mm and <10-mm polyps in a bowel cancer screening setting. We assessed whether OD-histology surveillance interval concordance exceeds the 90% Preservation and Incorporation of Valuable Endoscopic Innovations threshold required for implementation of a resect and discard strategy.  We also aimed to define a quality assurance process and assess patient acceptability.

DISCARD3 differs from earlier studies in that all 8 participating endoscopists were highly experienced, accredited bowel cancer screening colonoscopists. In addition, a robust quality assurance process was for the first time evaluated, and the patient perspective was explored with a survey and a focus group. 

We also performed a detailed root-cause analysis of all cases of high-confidence OD error and evaluated the economic impact of a resect and discard strategy.

We found that the learning curve for OD in a bowel cancer screening setting varies between individual operators, with most able to perform consistently with an accuracy of ≥75%. A resect and discard strategy for high-confidence ≤5-mm polyp ODs is feasible and safe, with performance exceeding the 90% surveillance interval concordance threshold (with British Society of Gastroenterology [BSG], European Society of Gastrointestinal Endoscopy [ESGE] and U.S. Multi-Society Task Force guidelines) required for implementation in clinical practice. 

For high-confidence OD of polyps <10 mm, the 90% surveillance interval threshold is exceeded for BSG and ESGE guidelines but not for U.S. guidelines. Most patients were satisfied with their procedures and supported an OD approach. 

We also proposed a quality assurance process to support implementation of OD in clinical practice. A full economic analysis and detailed evaluation of the likely causes of OD error will be published separately.

Optical diagnosis of adenomas and serrated lesions using narrow-band imaging. NBI, Narrow-band imaging.

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