| Infection percentage | Description | Antibiotic prophylaxis |
Clean (I) | 1.5% - 4.2% | Usually non traumatic. It presume that respiratory, genitourinary and digestive tract are not opened and the lack of technical mistakes. | Not necessary, except for the presence of risk factors and comorbidities. |
Clean-contaminated (II) | <10% | Surgical procedures in which there is the opening of respiratory, genitourinary and digestive tract in the absence of an evident contamination, or the opening of the oropharynx, genitor-urinary tract or biliary tract, unless clearly infected. It is also included in this category also any minor technical mistake. | Recommended. |
Contaminated (III) | 10% - 20% | Procedures following a frank contamination of gastrointestinal tract or after the opening of genitor-urinary or biliary tract with the presence of urine or infected bile. It is also included in this category also any major technical mistake. | Necessary (wide spectrum). |
Dirty (IV) | 20% - 40% | Procedures with a frank contamination, clinical infection in course, visceral perforation, purulent collections. | The usage of antibiotics is necessary for healing a pre-existing infections. |