The scope of surgical disinfection is mainly required to follow several principles. The clean part of the surgical incision should be disinfected from the surgical area to the periphery to expand the disinfection area, and if it is a contaminated area it should be disinfected from the periphery to the surgical area, with a minimum diameter of 30cm. In the case of surgical incisions in the lower abdomen, clean ones should also be disinfected from the surgical scheduled incision to the surrounding coated foam, up to the position of the flat nipple, on both sides to the posterior axillary line, and below to the upper 1/3 of the thigh, including the pubic area as well as the perineal area, and generally the pubic and perineal areas are the last disinfection steps. If there is a possibility of extending the incision during the operation, the skin disinfection should be expanded accordingly, usually six pieces of gauze with tincture of iodine, every two pieces of gauze, and the disinfection range should be reduced each time to prevent repeated contamination.