1. Inflammatory Bowel Disease Center, Yokohama City University Medical Center, Yokohama, Japan
2. Department of Gastroenterological Surgery, Yokohama City University Graduate School of Medicine, Yokohama, Japan
3. Department of Surgery, Yokosuka Kyosai Hospital, Yokosuka, Japan
4. Gastroenterological Center, Yokohama City University Medical Center, Yokohama, Japan
5. Department of Surgery, Yokohama City Minato Red Cross Hospital, Yokohama, Japan
6. Department of Surgery, Saiseikai Wakakusa Hospital, Yokohama, Japan
7. Department of Surgery, Saiseikai Yokohamashi Nanbu Hospital, Yokohama, Japan
8. Inflammatory Bowel Disease Center, Yokohama Municipal Citizen's Hospital, Yokohama, Japan