Postoperative fever
Fever of at least 38.0°C after surgery, worked up by the timing of onset rather than a single test. Most cases are self-limited, but the evaluation must exclude pulmonary embolism, necrotizing fasciitis, and malignant hyperthermia while directing source-specific treatment such as empiric antibiotics, anticoagulation, or urgent debridement.
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What this article covers
- Overview
Definition: postoperative fever is a temperature of at least 38.0°C (100.4°F) after surgery, a sign rather than a diagnosis; the workup exists to name the cause.
- Epidemiology
How common it is: fever develops in up to 40% of patients after surgery, and most episodes never yield an infectious source.
- Risk factors
Wound contamination class: contaminated wounds (gross gastrointestinal spillage, traumatic wounds over 12 to 24 hours old) and dirty-contaminated wounds (established peritonitis) carry the highest risk.
- Pathophysiology
Sterile inflammatory fever: tissue injury activates macrophages, releasing interleukin-6, tumor necrosis factor-alpha, and interferon-gamma; these pyrogens raise the hypothalamic set point…
- Clinical features
The five Ws and their windows: Wind (atelectasis) POD 1 to 2; Water (urinary tract infection) POD 3 to 5; Walking (deep vein thrombosis or pulmonary embolism) POD 5 to 7; Wound (surgical site…
- Differential diagnosis
Atelectasis: diminished breath sounds and low-grade fever on POD 1 to 2, but the radiograph shows no infiltrate, unlike pneumonia, and it resolves with incentive spirometry alone.
- Diagnosis
What establishes the cause: postoperative fever is confirmed by a single temperature of at least 38.0°C; establishing the cause is a POD-timed, stepwise workup, not one test.
- Management
First, stabilize the unstable patient: for hypotension, tachycardia, or crepitus or pain out of proportion, give intravenous crystalloid, draw blood cultures, start empiric therapy within one hour…
- Complications
Sepsis and septic shock: an untreated source, most often surgical site infection, pneumonia, or urinary tract infection, can progress to sepsis within days.
- Prognosis
Most fevers are self-limited: those before POD 3 with a benign examination resolve within hours and need no therapy.
- Prevention
Surgical site infection prophylaxis: a single preoperative dose of cefazolin (2 g intravenously under 120 kg, 3 g at 120 kg or more, or vancomycin 15 mg/kg for beta-lactam allergy) within 60 minutes…
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Related articles
- Necrotizing fasciitis
Necrotizing fasciitis is a rapidly progressive, life-threatening infection of the subcutaneous tissue and superficial fascia driven by vessel thrombosis and bacterial exotoxin production. The hallmark is pain out of proportion to visible skin findings, with crepitus, bullae, and woody induration in advanced disease. Diagnosis is confirmed by direct surgical exploration; the LRINEC score aids risk stratification. Treatment is emergent surgical debridement combined with broad-spectrum empiric antibiotics.
- Surgical site infections
A surgical site infection (SSI) is infection at or near an operative incision within 30 days of surgery, or 90 days with an implant. Diagnosis rests on purulent drainage, culture, or a surgeon opening the wound. Treatment is source control, drainage and debridement of necrotic tissue, plus culture-directed antibiotics.
- Pulmonary embolism
Pulmonary embolism is thrombus, usually from a lower-extremity deep vein thrombosis, obstructing the pulmonary arterial circulation and causing V/Q mismatch, right ventricular strain, and hypoxemia. Diagnosis follows Wells criteria (with PERC in low-risk patients) to sequence D-dimer, CT pulmonary angiography, and V/Q scanning, and management is risk-stratified anticoagulation escalating to thrombolysis or embolectomy for hemodynamic instability.
- Hospital-acquired pneumonia
Hospital-acquired pneumonia is a new pulmonary infiltrate with clinical signs of infection developing 48 hours or more after admission in a nonintubated patient, driven by gram-negative bacilli and Staphylococcus aureus rather than typical community organisms; empiric therapy is broad-spectrum antipseudomonal coverage started without delay and narrowed at 48 to 72 hours.
- Urinary tract infections (UTIs), including pyelonephritis
Urinary tract infection spans uncomplicated cystitis, presenting with dysuria, frequency, and suprapubic pain, through pyelonephritis, presenting with fever, flank pain, and costovertebral angle tenderness, most often from ascending Escherichia coli. Uncomplicated cystitis is treated empirically without culture using nitrofurantoin, trimethoprim-sulfamethoxazole, or fosfomycin, while pyelonephritis requires a pre-treatment urine culture and empiric fluoroquinolone or cephalosporin therapy, escalated to hospitalization and broader parenteral coverage for hemodynamic instability, obstruction, or failure to improve.
- Sepsis
Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection, identified by an acute rise in SOFA score of 2 points or more in a patient with known or suspected infection. Survival depends on recognizing the pattern early and completing the hour-1 bundle: lactate, blood cultures before antibiotics, broad-spectrum antibiotics such as cefepime 2 g IV every 8 hours, and 30 mL/kg crystalloid for hypotension or a lactate of 4 mmol/L or higher.