1. Department of Gastroenterology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004, P.R. China
2. Pathology Department, North China University of Science and Technology Affiliated Hospital, Tangshan, Hebie 063000, P.R. China
3. Department of Gastroenterology, Ordos Central Hospital, Ordos, Inner Mongolia Autonomous Region 017000, P.R. China
4. Department of Medical Laboratory, School of Clinical Medicine, Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004, P.R. China