Study characteristics.

* These two studies were identified from one literature. ** These two studies were identified from one literature. + This study did not describe their diagnostic criteria in detail. N.A.C., a previously described classification system developed on the base of characterization of colonic polyps using FICE; ICE-classification, i-Scan classification for endoscopic diagnosis which is a simple classification built upon Kudo classification and NICE classification; NICE, Narrow Band Imaging International Colorectal Endoscopic Classification; N, not mentioned. Study characteristics.