1. Department of Vascular Surgery, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi Province, 710061, P.R.China
2. Department of General Surgery, The First Affiliated Hospital of Xi’an Medical University, Xi’an, Shaanxi Province, 710077, P.R.China
3. Department of Gastroenterology, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi Province, 710061, P.R.China
4. Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA