Introduction Chromoendoscopy is one of several advanced endoscopic imaging techniques that have emerged in recent years. Chromoenedoscopy can enhance and facilitate mucosal observation of pit patterns in colorectal lesions. In this study we investigated the effectiveness of this technique by exploring the correlation between Kudo score and final histology.

Method This was a prospective study of all patients who had undergone endoscopic resection, by a single operator, between August 2007 and December 2012 in Bradford Royal Infirmary. Once a polyp was identified at colonoscopy, it was sprayed with Indigocarmine solution, assessed and then assigned a Kudo score (I–V). We recorded patients’ age, sex, polyp size and site, the procedure date, and the final histology. We then analysed the data by observing whether the assigned kudo score matched the final histology. A positive association was made if Kudo scores of I and II correlated with normal or hyperplastic histology, kudo scores of III and IV correlated with adenomatous histology, and if a Kudo score of V correlated with adenocarcinoma.

Results In total there were 185 polypectomy cases. Of these 14 cases were excluded either because a Kudo classification was missing (7 cases), or the histology was not available (7 cases). The final analysis was performed based on the remaining 171 cases. In 149 out of these 171 cases, the Kudo score matched the final histology (87%). There was no difference in correlation score, based on polyp size or location. However, the correlation score was higher in patients under 70 age group (93%), compared to those over 70 (82%). Also, the correlation score was higher in those undergoing the procedure in 2010 or later (90%) compared to those who had it pre-2010 (82%).

Conclusion Our results demonstrate a high correlation score between Kudo scoring and the final histology, using chromoendoscopy. Correlation scores improve over time with increasing exposure and practise. Characteristic pit patterns observed using chromoendoscopy helps to differentiate adenomatous from non-adenomatous polyps. In experienced hands, this technique provides a useful adjunct in the assessment of colorectal lesions, and can help make crucial decisions at the time of endoscopy.

Disclosure of interest None Declared.