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Post-Operative Fever

I. Principles

  • Fever = temperature > 38.0°C (100.4°F) in the immediate post-operative setting.
  • May be benign (inflammatory response, blood products) or pathologic (infection, thromboembolic, ischemic).
  • Always stratify by time since surgery, severity, and patient stability.
  • Unstable patient with fever = sepsis until proven otherwise.

II. Timeline-Based Differential

Post-Op Timing Common Etiologies High-Risk / Dangerous Causes
< 48 hours Inflammatory response, hematoma, aspiration, transfusion reaction, atelectasis Early pneumonia, intra-op contamination, line infection
48–72 hours Pneumonia, UTI, phlebitis, catheter infection Anastomotic leak, sepsis
3–7 days Surgical site infection, pneumonia, UTI, C. difficile colitis Intra-abdominal abscess, anastomotic leak, empyema
> 7 days DVT/PE, line sepsis, drug fever Deep abscess, septic pelvic thrombophlebitis

III. Stepwise Evaluation

Step 1 – Confirm Fever

  • Verify measurement and source, repeat if uncertain.
  • Review trend, maximum temperature, and fever pattern (isolated vs persistent vs spiking).

Step 2 – Assess Stability

  • Vitals: HR, BP, O2 sat, RR.
  • Sepsis screen: hypotension, tachypnea, altered mental status, oliguria.

Step 3 – History and Exam

  • History: cough, sputum, dysuria, wound pain/drainage, diarrhea, calf pain/swelling, meds/blood products.
  • Exam: chest, surgical wounds, drains, Foley, IV/central lines, extremities.

Step 4 – Initial Workup

  • Basic set (almost always):
  • CBC with differential
  • BMP
  • Blood cultures ×2
  • Urinalysis ± urine culture
  • Chest X-ray
  • Targeted testing (if indicated):
  • Sputum culture (productive cough)
  • Stool toxin/PCR (diarrhea, recent antibiotics)
  • CT abdomen/pelvis with IV contrast (abdominal tenderness, tachycardia, leak/abscess concern)
  • Duplex ultrasound (suspected DVT)
  • Line cultures (if catheter infection suspected)

IV. Management

  • Stable patients
  • Complete evaluation before empiric antibiotics

  • Supportive care: antipyretics, pulmonary toilet, incentive spirometry, ambulation, hydration

  • Unstable patients

  • Treat as sepsis
  • Cultures, broad-spectrum antibiotics, IV fluids

  • Search for and initiate source control (abscess drainage, remove infected line, debride wound)

  • Source-directed therapy

  • Abscess → drainage
  • SSI → open wound, culture, drainage
  • Pneumonia/UTI → targeted antibiotics
  • C. difficile → oral vancomycin or fidaxomicin
  • Line sepsis → line removal

V. Red Flags – Call Senior Immediately

  • Hemodynamic instability (hypotension, tachycardia, hypoxia)
  • Peritonitis or rigid abdomen
  • Fever with chest pain, arrhythmia, or sudden hypoxia (possible PE/MI)
  • Purulent, feculent, or bilious drainage from wound or drains
  • Temperature > 39°C without clear source

VI. Intern Pearls

  • First 24h fevers often non-infectious, but rule out aspiration, transfusion reaction, necrotizing infection.
  • Always inspect lines, drains, Foley, wounds.
  • Drug fever is rare and a diagnosis of exclusion.
  • Remember: Sepsis = Source control + Antibiotics + Resuscitation.

VII. Quick Reference Table

Initial Workup

Test Indication
CBC with diff Almost always
BMP Baseline and renal function
Blood cultures ×2 Unexplained fever or unstable
Urinalysis ± UCx Foley or dysuria
Chest X-ray POD >2, cough, hypoxia
CT A/P with IV contrast Abdominal tenderness, leak/abscess concern
Duplex US Suspected DVT
Stool toxin/PCR Diarrhea, recent antibiotics
Line cultures Suspected line sepsis

VIII. References

  1. Bartlett JG, et al. Postoperative fever: clinical evaluation and management. Clin Infect Dis. 2002;34(4):512–518.
  2. Berríos-Torres SI, et al. Centers for Disease Control and Prevention Guideline for the Prevention of Surgical Site Infection. JAMA Surg. 2017;152(8):784–791.
  3. Calandra T, Cohen J. International Sepsis Forum Consensus Conference on Definitions of Infection in the ICU. Crit Care Med. 2005;33(7):1538–1548.
  4. Dellinger RP, et al. Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock. Crit Care Med. 2013;41(2):580–637.

Key Takeaways

  • Always verify fever, assess stability, and apply timeline-based differential.
  • Early fevers often benign; late fevers usually infectious.
  • Workup should be systematic and source-driven.
  • Unstable post-op patient with fever = treat as sepsis until proven otherwise.