1. Department of Pediatric Surgery, Hyogo College of Medicine, Nishinomiya, Japan.
2. Department of Pediatric Surgery, Osaka University Graduate School of Medicine, Suita, Japan.
3. Department of Pediatric Surgery, Osaka City General Hospital, Osaka, Japan.
4. Department of Pediatric Surgery, Kindai University Nara Hospital, Ikoma, Japan.
5. Department of Pediatric Surgery, Osaka Women's and Children's Hospital, Izumi, Japan.