Table 1.

CDC surgical wound classification, reprinted from Mangram et al¹⁰

Wound classification	Description
Class I/clean	An uninfected operative wound in which no inflammation is encountered and the respiratory, alimentary, genital or uninfected urinary tract is not entered. In addition, clean wounds are primarily closed and, if necessary, drain with closed drainage. Operative incisional wounds that follow non-penetration (blunt) trauma should be included in this category if they meet the criteria.
Class II/clean–contaminated	An operative wound in which the respiratory alimentary, genital or urinary tracts are entered under controlled conditions and without unusual contamination. Specifically, operations involving the biliary tract appendix, vagina and oropharynx are included in this category, provided no evidence of infection or major break in technique is encountered.
Class III/contaminated	Open fresh, accidental wounds. In addition, operation with major breaks in sterile technique or gross spillage from the gastrointestinal tract, and incisions in which acute, non-purulent inflammation is encountered are included in this category.
Class IV/dirty-Infected	Old traumatic wounds with retained devitalised tissue and those that involve existing clinical infection or perforate viscera.

CDC, Centers for Disease Control and Prevention.