In postoperative fever classification, which cause is associated with 12-24 hours after surgery?

• A. Atelectasis
• B. Urinary tract infection
• C. Deep vein thrombosis
• D. Wound infection

Answer: (A)

Postoperative fevers that appear within the first day are often due to the body’s inflammatory response to surgical trauma and, in many cases, atelectasis from shallow breathing after anesthesia. When small areas of the lung collapse (atelectasis), local inflammation occurs and inflammatory mediators rise, which can push the body's temperature up within about 12–24 hours. This keeps the fever typically mild and self-limited, especially in patients with limited deep breaths due to pain or chest wall restriction.

Urinary tract infection tends to develop later, usually after catheter use, and wound infection or deep vein thrombosis generally present several days after surgery, not within the first 24 hours.