The majority of wound infections occur 3-5 days after surgery because tissue healing pathologically takes about 48 hours to form fibrous connective tissue. If there are factors of poor tissue healing, including poor local blood supply or underlying diseases in the body, such as elevated blood sugar due to diabetes or bacterial infection in the local wound, there is no way to form fibrous connective tissue by about 48 hours. At this time, the infected bacteria grow and multiply in large numbers, resulting in local septic infection, and in severe cases, even into the bloodstream causing toxemia, with local manifestations of redness, swelling, heat and pain, and systemic manifestations of chills and fever. Therefore, the general wound dressing change after surgery in 2-3 days after surgery, we should closely observe the wound for redness, swelling, heat and pain, and be alert to the possibility of infection.