Differential Diagnosis for Post-Op Fever

Single Most Likely Diagnosis

• Surgical Site Infection (SSI): This is often the most common cause of post-operative fever, occurring due to bacterial contamination of the surgical site during or after surgery. The risk factors include the type of surgery, patient's overall health, and perioperative care practices.

Other Likely Diagnoses

• Atelectasis: A common pulmonary complication post-surgery, especially after general anesthesia, leading to fever. It occurs due to the collapse or closure of a lung resulting in reduced or absent gas exchange.
• Urinary Tract Infection (UTI): Particularly in patients with urinary catheters, UTIs are a frequent cause of post-operative fever. Bacterial colonization of the catheter and urinary tract can lead to infection.
• Pneumonia: Post-operative pneumonia can occur, especially in patients who have undergone major surgery, have limited mobility, or have been on mechanical ventilation.
• Deep Vein Thrombosis (DVT): Although less commonly associated with fever, DVT can cause a low-grade fever and is a significant concern in post-operative patients due to immobility.

Do Not Miss Diagnoses

• Sepsis: A life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. Early recognition and treatment are crucial.
• Malignant Hyperthermia: A rare but life-threatening medical emergency triggered by certain drugs used for general anesthesia. It requires immediate intervention.
• Transfusion-Related Acute Lung Injury (TRALI): A serious blood transfusion complication that can cause non-cardiogenic pulmonary edema and fever.
• Antibiotic-Associated Clostridioides difficile (C. diff) Infection: Can cause severe diarrhea and fever, and is associated with antibiotic use, which is common post-operatively.

Rare Diagnoses

• Adrenal Insufficiency: Although rare, it can cause fever among other symptoms, particularly in patients who have been on long-term steroid therapy and have had it abruptly discontinued.
• Thyroid Storm: A life-threatening complication of untreated or undertreated hyperthyroidism, which can be precipitated by surgery.
• Neuroleptic Malignant Syndrome (NMS): A rare, life-threatening disorder caused by an adverse reaction to neuroleptic or antipsychotic drugs, which can be used in the perioperative period for various reasons.