1. Division of Gastrointestinal and Pediatric Surgery, Department of Surgery, School of Medicine Tottori University Faculty of Medicine 36‐1 Nishi‐cho Yonago 683‐8504 Japan
2. Department of Surgery Kansai Medical University 2‐5‐1 Shinmachi, Hirakata Osaka 573‐1010 Japan
3. Department of Surgery Japanese Red Cross Tottori Hospital 117 Shotoku‐cho Tottori 680‐8517 Japan