Hood cap-assisted chromocolonoscopy using indigocarmine is expected to improve the detection rate of colorectal polyps, especially adenomatous polyps. Therefore, aim of the present study was to evaluate the usefulness of hood cap-assisted chromocolonoscopy in routine colonoscopic examinations.

From January, 2013 through March, 2013, a total of 86 patients were enrolled (M:F=33:53, mean age=60 years). For each patient, hood cap-assisted colonoscopic examination was performed, followed by hood cap-assisted chromocolonoscopy using 0.2% indigocarmine from the cecum to the hepatic flexure. Total numbers and characteristics of polyps were compared before and after indigo carmine dye spraying.

Prior to dye spraying, 48 polyps were found in 37 patients, and after dye spraying, 53 additional polyps were found in 34 patients. Of these undetected polyps, 45 (85%) were small sized polyps (≤0.5 cm). Histologically, 19 (36%) were adenomatous polyps, and of these, 15 (28%) were tubular adenomas and 4 (8%) were serrated adenomas. As for the polyp detection rate, there was no difference between the expert and the non-expert groups.

Hood cap-assisted chromocolonoscopic examination using indigocarmine was helpful in detecting cecum and ascending colon polyps, especially small sized polyps (<0.5 cm) and neoplastic polyps.