Two days after intramedullary nailing of a femoral shaft fracture, a 25-year-old man develops tachypnoea, confusion, and a petechial rash over the chest and axillae. Pulse oximetry shows SpO2 of 88 percent. The most likely diagnosis is:

• A Fat embolism syndrome ✓
• B Pulmonary thromboembolism
• C Transfusion related acute lung injury
• D Hospital acquired pneumonia

Explanation

Fat embolism syndrome classically appears 24 to 72 hours after long bone fracture or its instrumentation, with the triad of respiratory distress, cerebral involvement, and a petechial rash in the chest, axillae, and conjunctivae. Thromboembolism typically lacks petechiae and occurs later in immobile patients. TRALI follows transfusion directly, and pneumonia evolves over days with fever and purulent sputum rather than abrupt hypoxia with rash.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.