Postoperative fever at 48 hours is most commonly due to which cause?

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

Answer: (C)

Postoperative fever timing helps guide the likely causes. About two days after surgery, a fever raises concern for a thrombotic complication because immobility and surgical injury create a prothrombotic state, making deep vein thrombosis a plausible and important cause to consider in this window. DVT can provoke fever as part of the inflammatory response, and recognizing it early is key to preventing progression to pulmonary embolism, so it’s treated and investigated promptly.

Urinary tract infection and wound infection typically show up later in the postoperative course, after a few days as bacterial colonization or wound healing processes evolve. Atelectasis has historically been cited as a common early cause of fever, but the clinical emphasis around the 48-hour mark in many postoperative patients is on DVT because of the immediate thrombotic risk after surgery and the potential for serious consequences if missed.