This is a randomized controlled trial comparing the use of Narrow-Band Imaging (illumination of the colon in blue light)versus standard white light for the detection of serrated lesions in the proximal colon (the colon proximal to the splenic flexure). Recent studies have indicated that colonoscopy is more effective in preventing cancer in the left side of the colon than the right side of the colon. The reasons for this difference may be partly biologic, in that a special group of polyps known as serrated polyps, particularly sessile serrated adenomas, are located primarily proximal to the splenic flexure. These lesions share molecular features with a group of cancers that occur primarily in the proximal colon. These molecular features include CpG island methylator phenotype (CIMP) and microsatellite instability. These lesions are endoscopically subtle in that they are often flat, have the same color as the surrounding mucosa, and are hard to differentiate from normal mucosa. Narrow-Band Imaging has anecdotally been used to highlight the appearance of these lesions. This study will test whether Narrow-Band Imaging increases the detection of serrated lesions in a randomized controlled trial.