The goal of this exploratory validation study is to compare levels of expertise (or non-expertise) between GI fellows and experts with the varix trainer. The main question it aim to answer is:

Can the varix trainer distinguish levels of expertise (or non-expertise) between novices and experts for specific skills (torque, small wheel and retroflexion techniques)? Does the training with the varix trainer improves these specific skills of GI fellows? Participants will do the pre-training test, practicing eight-sessions (each session is approximately 15minutes) and then do the post-training test.

Inclusion Criteria:

• We enrolled participants from Ramathibodi hospital King Chulalongkorn Memorial hospital Siriraj hospital Rajavithi hospital Vajira hospital Nanthana-Kriangkrai Chotiwattanaphan Institute of Gastroenterology and Hepatology Srinagarind Hospital

  1. Expert (> 1,500 EGD)
  2. Trainees (First and second year fellow)

Exclusion Criteria:

• Deny to participate in our study