Efficacy of WASP Classification in the Histological Evaluation of Diminutive Colorectal Polyps

Adenomas, serrated adenomas and hyperplastic polyps are polypoid lesion in the colorectum. At the present moment, all polyps should be resected endoscopically, although only adenomas and serrated adenomas, but not hyperplastic polyps have the potential to develop colorectal cancer. Some studies have investigated the value of the narrow-band imaging (NBI) on histological prediction of the polyp. This method is conducted in real time during colonoscopy, which leads to simplification of diagnostic procedures. For instance, it would be conceivable to resect diminutive polyps and discard them without further assessment by a pathologist. One problem in this context is a correct differentiation between hyperplastic polyps and serrated adenomas. These two polyp entities are known to show similar optical features. However, while serrated adenomas are premalignant lesions hyperplastic polyps have benign histology and never develop into cancer. It is therefore important to sufficiently distinguish hyperplastic polyps from serrated lesions.

In this study the investigators want to investigate whether the use of NBI would be capable to get accuracy of optical polyp predictions by more than 90% using the WASP (Workgroup serrAted polypS and Polyposis) classification. NBI is a light filter tool which can be activated by pressing a button at the endoscope. The use of NBI leads to an endoscopic picture which appears blue and enables endoscopists to better assess surface structures and vascular patterns. All polyps will be resected and send to pathology for further microscopic assessment. After completing the trial the investigators aim to compare accuracy of the optical diagnosis.