1. Department of Surgery Keio University School of Medicine Tokyo Japan
2. Department of Pediatric Surgery and Transplantation Kumamoto University Graduate School of Medical Sciences Kumamoto Japan
3. Department of Surgery Saitama City Hospital Saitama Japan
4. Department of Pediatric Surgery Keio University School of Medicine Tokyo Japan
5. Department of Hepato‐Biliary‐Pancreatic and Gastrointestinal Surgery International University of Health and Welfare School of Medicine Chiba Japan
6. Center for Infectious Disease and Infection Control Keio University School of Medicine Tokyo Japan