A surgical fever is defined as a temperature greater than 101.5°F or 38.5°C. The major etiologies for postoperative fever that should always be considered include atelectasis, pneumonia, urinary tract infection, intra-abdominal infection or leak, wound infection, and deep venous thrombosis. Other processes such as malignant hyperthermia, superficial thrombophlebitis, C. difficile colitis, endocarditis, and line infections should also be considered given the appropriate circumstances.
It is often helpful to categorize these various etiologies by the postoperative day on which they are most likely to occur (see Table 39-1). It is, however, important to note that any of these processes can occur on any postoperative day.
It is important to remember that any source of infection can lead to bacteremia, or sepsis. Although a full discussion of the SIRS response and sepsis is covered in other chapters, the astute clinician should always be looking for systemic signs of infection whenever presented with a patient with postoperative fever.