Adjunctive use of chromoendoscopy may improve the diagnostic performance of narrow-band imaging for small sessile serrated adenoma/polyp

Background and Aim: Endoscopic diagnosis of sessile serrated adenoma/polyp (SSA/P) is challenging because of their subtle appearance. Narrow-band imaging (NBI) is useful for diagnosis, but its utility with concurrent chromoendoscopy (CE), especially to detect small SSA/P, is unproven. Methods: This prospective study enrolled 367 consecutive patients who underwent screening colonoscopy with the finding of serrated polyps. Patients were divided into derivation and validation cohorts: Diagnostic criteria using different endoscopic modalities were generated by regression analysis in the derivation cohort and were validated in the validation cohort for sensitivity, specificity, and accuracy. Results: There were 180 patients with 119 SSA/P and 147 hyperplastic polyps (HP) in the derivation cohort and 187 patients with 177 SSA/P and 125 HP in the validation cohort. With white-light endoscopy plus NBI, mucus cap, surface grooves, and expanded crypt were most associated with SSA/P. With white-light endoscopy plus CE, II-O pit pattern, mucus cap, and superficial telangiectasia were most associated with SSA/P. With the combined use of these three modalities, II-O pit pattern, mucus cap, and surface grooves were most associated with SSA/P. For large serrated polyp, NBI in combination with CE had a better accuracy than NBI alone (91% vs 86%, P = 0.025) to distinguish SSA/P from HP. CE alone had a better accuracy than NBI alone for distinguishing small SSA/P from small HP (85% vs 72%, P < 0.0001). Conclusion: Compared with NBI alone, adjunctive use of CE can improve the diagnostic accuracy for distinguishing SSA/P from HP, especially for small SSA/P.