1. Department of General Surgery; Heilongjiang Province Hospital; Harbin Heilongjiang 150000 China
2. The 21 Ward of General Surgery; Daqing Oil Field General Hospital; Daqing Heilongjiang 163000 China
3. Department of Gastroenterology; Heilongjiang Province Hospital; Harbin Heilongjiang 150000 China
4. The 19 Ward of General Surgery; Daqing Oil Field General Hospital; Daqing Heilongjiang 163000 China