Background and study aim: The ‘diagnose-and-leave-in’ policy has been established to reduce risks and costs related to unnecessary polypectomies in the average-risk population. In Lynch syndrome individuals, due to accelerated carcinogenesis, the general recommendation is to remove all polyps, irrespective of size, location and appearance. We evaluated the feasibility and safety of the ‘diagnose-and-leave-in’ strategy in Lynch syndrome individuals. Patients and methods: We performed a post-hoc analysis based on per-polyp data from a randomized, clinical trial conducted by 24 dedicated colonoscopists at 14 academic centres, in which 256 individuals with confirmed Lynch syndrome underwent surveillance colonoscopy from July 2016 to January 2018. In vivo optical diagnosis with the level of confidence of all detected lesions were obtained before polypectomy using virtual chromoendoscopy alone or with dye-based chromoendoscopy. Our primary outcome was the negative predictive value (NPV) for neoplasia of high-confidence optical diagnosis among diminutive (≤ 5 mm) rectosigmoid lesions. Histology was the reference standard. Results: Of 147 rectosigmoid lesions, 128 were diminutive. In 103 of the 128 lesions (81%) , the optical diagnostic confidence was high, showing a NPV of 96.0% (95% confidence interval, [88.9%–98.6%]) and accuracy of 89.3% (95% confidence interval, [81.9%–93.9%]). By following the ‘diagnose-and-leave-in” policy, we would have avoided 59% (75/128) unnecessary polypectomies at expenses of 2 diminutive low-grade dysplasia adenomas and 1 diminutive sessile serrated lesion that would have been left in situ. Conclusion: In Lynch syndrome patients, the “diagnose-and-leave-in strategy” for diminutive rectosigmoid polyps would be feasible and safe.

No abstract

No abstract

No abstract

No abstract