postoperative fever is common in the first few days following major surgery secondary to physiologic responses from surgery.
Surgery is tough on the body, and it’s not unusual to have a fever during the first 48 hours after surgery. Any fever that develops in the hours or days after a surgical procedure is considered a postoperative fever.
What is Pathophysiology of postoperative fever?
Interleukins, tumor necrosis factor-alpha, and interferon-gamma act on the preoptic area of the hypothalamus which releases fever-inducing prostaglandins.
There are many factors that influence "cytokine" releases, including the magnitude of trauma, genetics, and bacterial endotoxins and exotoxins that may be present in the blood during surgery