Clin Endosc.  2022 Sep;55(5):645-654. 10.5946/ce.2022.048.

Optical diagnosis by near-focus versus normal-focus narrow band imaging colonoscopy in colorectal polyps based on combined NICE and WASP classification: a randomized controlled trial

  • 1NKC Institute of Gastroenterology and Hepatology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand
  • 2Division of Pathology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand


Narrow Band Imaging (NBI) International Colorectal Endoscopic (NICE) and Workgroup Serrated Polyps and Polyposis (WASP) classifications were developed for optical diagnosis of neoplastic and sessile serrated polyps, respectively. Near-focus NBI with NICE combined with WASP criteria for optical diagnosis of colonic polyps has not yet been evaluated. We aimed to compare the accuracy of near-focus NBI (group A) with normal-focus NBI (group B) in real-time optical diagnosis of colorectal polyps using combined NICE and WASP criteria.
Among 362 patients, 118 with 227 polyps were recruited. Groups A and B included 62 patients with 130 polyps (three lost polyps) and 56 patients with 106 polyps (six lost polyps), respectively. Optical diagnoses were compared with pathological reports.
The accuracy of optical diagnosis of neoplastic polyps in groups A and B was not significantly different (76% vs. 71%, p=0.52). WASP criteria provided all false positive diagnoses of sessile polyps as serrated polyps in 31 (16.2%) patients.
Near-focus NBI was not superior to normal-focus NBI in optical diagnostics of neoplastic polyps using NICE criteria. In our study, WASP classification yielded all false positives in the diagnosis of sessile serrated adenomas/polyps. Routine real-life optical diagnosis of polyps is still unadvisable.


Colorectal polyp; Near-focus narrow band imaging; NICE classification; Optical diagnosis; WASP classification


  • Fig. 1. Flow diagram of the study.


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