The aim of the study is to develop a score system in order to differentiate adenomatous polyps, hyperplastic polyps and serrated adenomas on the basis of optical features. Endoscopic images of colorectal polyps will be collected from a prospectively managed database. Histopathological diagnoses are available for all polyps. Histopathological diagnoses serve as gold standard in this study.

In the first phase of the study optical features of serrated adenomas are extracted from the database. Discriminators are then defined on the basis of the extracted features. In the second phase a test set of high quality pictures are provided to both novices and experts of colorectal endoscopy. Participants are asked to use the above named discriminators in order to rate pictures and to classify polyps into three classes (adenomatous polyps, hyperplastic polyps and serrated adenomas). In the third phase of the study accuracy of optical bases diagnoses is calculated by comparing optically derived diagnoses with histopathological diagnoses (gold standard).

Inclusion Criteria:

• indication for colonoscopy
• patients >= 18 years

Exclusion Criteria:

• pregnant women
• indication for colonoscopy: inflammatory bowel disease
• indication for colonoscopy: polyposis syndrome
• indication for colonoscopy: emergency colonoscopy e.g. acute bleeding
• contraindication for polyp resection e.g. patients on warfarin

Patients undergoing routine colonoscopy