1. Division of Gastroenterology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
2. Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
3. Division of Colorectal surgery, Department of Surgery, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
4. Department of Pathology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand