The results of the preoperative four tests are more accurate, and if the test results are negative, the possibility of infection can be ruled out. Preoperative four mainly refers to hepatitis B two half, hepatitis C, syphilis, AIDS four infectious disease examination, generally whether emergency surgery or elective surgery, before the operation need to carry out the examination, because of the sterilization of surgical instruments and postoperative treatment requirements are different from those of other patients, and generally encountered in the AIDS, syphilis positive need to be promptly reported. In general, the results of these four tests are more accurate, and a negative test can generally rule out the possibility of infection, but due to the different requirements of hospitals, different hospitals may not recognize the results of other hospitals.