1. Department of Pediatric Surgery, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
2. Department of Pediatric Surgery, Juntendo University School of Medicine, Tokyo, Japan.
3. Department of Pediatric Surgery, The University of Tokyo Hospital, Tokyo, Japan.
4. Department of Pediatric Surgery, Saitama Children's Hospital, Saitama, Japan.
5. Department of Pediatric Surgery, Shizuoka Children's Hospital, Shizuoka, Japan.
6. Department of Pediatric Surgery, Tokyo Women's Medical University, Tokyo, Japan.
7. Department of Pediatric Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.