Colorectal cancer is the third most common malignancy worldwide and the second leading cause of cancer related death with approximately 880 792 deaths every year (9,2% of the global yearly 9.6 million cancer deaths). Screening for polyps is done by colonoscopy, which is considered the gold standard for screening and removal of polyps and has been proven to reduce the global colorectal cancer burden significantly. Endoscopic removal of polyps is preferred because of its efficiency, cost-effectiveness, and safety in comparison to surgery.

Endoscopic tip control is a fundamental component of high quality endoscopy. Endoscopic procedures are complex processes where cognitive processing and motoric output need to be perfectly aligned. This is reflected in endoscopic tip control. It is indispensable in every step of endoscopy: during insertion of the endoscope, where the tip of the endoscope needs to reach the caecum/terminal ileum/duodenum, without discomfort for the patient if under light sedation, during withdrawal of the endoscope in order not to miss any lesions, and also during every endoscopic treatment whether it is a simple polypectomy or a complex therapeutic procedure performed by expert endoscopists.

However, there is currently no tool available to assess endoscopic tip control. And very little is known about educating it.

The investigators developed a new, web-based scoring system to assess tip control. The intent of this study is to validate this novel tool so it can be used to assess endoscopists and evaluate their progress when training in endoscopy.

This study takes place at the University Hospital Ghent, which is a tertiary care center for gastrointestinal endoscopy. The investigators will validate the tool in this study, through assessment of endoscopists of varying experience while they use a technique of snare tip soft coagulation on the margin of a polypectomy defect. This technique has proven its use in preventing recurrence after polypectomy. The technique uses the tip of a snare (used to resect polyps) to deliver thermal energy to the margin of a polypectomy, also called margin ablation. Thermal energy is applied by a hit on a pedal (operated with the foot), every hit needs to be exactly on the margin of the defect (not in the defect, not on normal mucosa around the defect). This requires a very steady and controlled handling of the endoscope and is an ideal technique to assess endoscopist's tip control. The score system will calculate the accuracy (number of correct hits over number of wrong hits) of tip control per second.

Inclusion Criteria:

• Endoscopists who perform endoscopic mucosal resections (EMR) at the University Hospital of Ghent, Belgium (UZ Gent)
• Patients, > 18 years of age, referred for EMR needing snare tip soft coagulation of the defect margins.

Exclusion Criteria:

• Endoscopists who do not consent to the study
• Patients who do not consent to the study

Endoscopists: all endoscopist (varying experience) performing polypectomy at the University Hospital of Ghent, Belgium (UZ Gent)

Patients: all patients undergoing endoscopic mucosal resection of colorectal polyps