1. Department of Anorectal Surgery, Tangxian People's Hospital in Hebei Province, Baoding, China.
2. Department of Anorectal Surgery, Baoding Second Hospital, Baoding, China.
3. Department of Pathology, Tangxian People's Hospital in Hebei Province, Baoding, China.
4. Medical Record Room, Tangxian People's Hospital in Hebei Province, Baoding, China.
5. Department of General Surgery, The Secondary Hospital of Tianjin Medical University, Tianjin, China.