Postoperative fever
Postoperative fever refers to an elevated body temperature occurring after a recent surgical procedure. Diagnosing the cause of postoperative fever can sometimes be challenging; while fever in this context may be benign, self-limited, or unrelated to the surgical procedure, it can also be indicative of a surgical complication, such as infection.
Causes
The most common causes of postoperative fever are often summarized for medical students by a mnemonic beginning with the letter W. The classic list consists of five W's – Wind, Water, Wound, Walking, and Wonder Drugs, but two other causes should also be considered – Wing/Waterway and abscess. There is a characteristic timeframe after surgery when many of these complications tend to develop.| Category | Day | Description |
| Wind | POD 1-2 | the lungs, i.e. pneumonia, aspiration, and pulmonary embolism; atelectasis has been commonly cited as a cause of post-operative fever, but supporting evidence is lacking |
| Water | POD 3-5 | urinary tract infection, possibly catheter-associated |
| Wound | POD 5-7 | infection of the surgical incision, either superficial or deep |
| abscess | POD 5-7 | infection of an organ or space |
| Walking | POD 5+ | deep vein thrombosis or pulmonary embolism |
| Wonder drugs or “What did we do?” | Anytime | drug fever or reaction to blood products, either a febrile non-hemolytic transfusion reaction or transfusion-related acute lung injury |
| Wing/Waterway | Anytime | bloodstream infection, phlebitis, or cellulitis related to intravenous lines, either central or peripheral |
Other important causes of early post-operative fever that are omitted from this list include malignant hyperthermia, a potentially life-threatening but treatable response to inhalational anesthetic and paralytic agents.
Early postoperative fever has often been ascribed to atelectasis, or splinting, but it is most likely part of a natural and non-infectious inflammatory response to the tissue injury sustained during surgery; it generally requires no medical intervention except antipyretics and extra fluid intake.
Workup
The diagnostic workup of post-operative fever is guided by the potential etiologies on the differential diagnosis. The patient's surgical and post-operative course should be reviewed in detail, noting whether the patient has been regularly using an incentive spirometer or not, whether a Foley catheter was/is in place, what medications s/he has received, etc. The patient should be asked if s/he is having any pain or other symptoms such as coughing or dysuria, which may help to localize the source of the fever. A thorough physical exam should be conducted, auscultating the lungs, noting erythema or drainage from the surgical incision, evaluating IV sites, noting lower extremity edema, etc.Laboratory testing and imaging is generally deferred for evaluation of fever that occurs within the first 48 hours post-operatively, unless prompted by specific findings in the history and physical exam. Beyond 48 hours, testing routinely includes urine and blood cultures as well as a chest X-ray.