Colon cancer is the second most common cause of death among cancer-related deaths in Germany. Precancerous lesions such as adenomas can be detected efficiently by colonoscopy. To provide high quality in colonoscopy several quality parameters have been postulated in the past. The adenoma detection rate (ADR) is one of those parameters. Empirical data suggest that a detection rate of 20% should be demanded. Detection rates are influenced by a multitude of circumstances such as bowel cleanness. The facts that detection rates vary between colonoscopists suggests that leaning effects may also play a role. It is not known how ADR and other quality parameters evolve while trainees improve their skills in colonoscopy. The investigators postulate that a learning curve exists. The investigators therefore plan to evaluate chronologically the findings of trainee colonoscopists. A particular performance in detecting adenomas shall be calculated in relation to the amount of examinations performed.

Inclusion Criteria:

• colonoscopy performed at the Technical University Munich, Germany

Exclusion Criteria:

• colonoscopy performed for the purpose of polypectomy

Endoscopy Department of a university Hospital