To study the application value of narrow-band image international colorectal endoscopic (NICE) classification under non-magnifying endoscopy in the accuracy of colorectal polyp judgment, and to clarify the learning curve of NICE classification application of endoscopes with different experiences.

1674 pictures of colorectal polyps from the Sixth Affiliated Hospital of Sun Yat-sen University from December 2019 to April 2020 were collected. Three junior physicians and one senior physician were respectively used for NICE classification. Pathological diagnosis was taken as the gold standard, and the accuracy rate was calculated and the learning curve was drawn.

The accuracy of NICE classification was 88% and 95.6%, respectively, for primary and senior physicians. The accuracy rates of primary and senior physicians in the diagnosis of inflammatory hyperplasia and invasive cancer were 87.4% and 84%, 99.2% and 100%, respectively, with no statistically significant difference (P>0.05). The accuracy of adenoma and early cancer was 63.2% and 90.7%, respectively, with statistically significant difference (P=0.001). The Kappa values of the preliminary and senior physicians for the detection of the consistency between NICE typing and pathological results were 0.8 and 0.93, respectively. After 900 and 350 images of colorectal polyps were observed by primary and senior physicians, the accuracy of judgment was nearly 100% and the fluctuation was reduced.

The overall accuracy of NICE classification for colorectal polyps under non-magnifying endoscopy is high, and endoscopists can achieve high accuracy after learning and accumulating a certain number of endoscopic images, which is easy for clinical promotion.