1. Postgraduate Program of Anesthesiology, Surgical Sciences and Perioperative Medicine, University of São Paulo, Rua Dr. Ovídio Pires de Campos, 255 - Cerqueira César, São Paulo, São Paulo 05403-000, Brazil
2. Surgery and Anatomy Department, Division of Gastrointestinal Surgery, Faculty of Medicine of Ribeirão Preto, Ribeirão Preto, Brazil
3. Gastrointestinal Endoscopy Unit, Gastroenterology Department, University of São Paulo Medical School, São Paulo, SP, Brazil
4. Department of Surgery, Federal University of Paraná, Curitiba, Brazil
5. Department of Surgery, University of São Paulo, São Paulo, Brazil