What is considered a postoperative fever (postoperative pyrexia)?

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From the Guidelines

A surgical fever is typically defined as a body temperature of 38.5°C or higher, occurring after a surgical procedure, and warrants investigation if it persists beyond 48 hours, exceeds 39°C, or is accompanied by other concerning symptoms. According to the most recent and highest quality study 1, fever in the early postoperative period (within 48 hours) is usually non-infectious in origin. However, once a patient is 96 hours postoperative, fever is likely to represent infection. The management of surgical fever depends on the cause, but may include antipyretics, adequate hydration, and appropriate antibiotics if infection is confirmed.

Key Considerations

  • Early surgical fevers (within 48 hours) are often due to the normal inflammatory response to tissue trauma or atelectasis (collapsed lung tissue) 1.
  • Fevers occurring 3-5 days post-surgery may indicate wound infections, urinary tract infections, or pneumonia, while those appearing after 5 days might suggest deep surgical site infections or other complications like deep vein thrombosis 1.
  • A chest radiograph is not mandatory for evaluation of postoperative fever unless respiratory rate, auscultation, abnormal blood gas, or pulmonary secretions suggest a high probability of utility 1.
  • Urinary tract infection is common postoperatively because of the use of urinary drainage catheters, and the duration of catheterization is the most important risk factor for the development of nosocomial cystitis or pyelonephritis 1.
  • New or persistent fever days after surgery should raise a strong suspicion of persistent pathology or a new complication, and it is mandatory to remove the surgical dressing to inspect the wound 1.

Recommendations

  • Surgical fevers should be investigated if they persist beyond 48 hours, exceed 39°C, or are accompanied by other concerning symptoms.
  • Antipyretics like acetaminophen (500-1000mg every 6 hours) and adequate hydration may be used to manage surgical fever.
  • Incentive spirometry may be used to prevent atelectasis.
  • Appropriate antibiotics should be used if infection is confirmed.

From the Research

Definition of Surgical Fever

  • Surgical fever is defined as a core temperature of ≥38.2 degrees C for at least 72 consecutive hours 2
  • Postprocedure fevers vary in the timing of their occurrence, duration, and severity, and do not all have an infectious cause, but they all require thorough investigation to rule out life-threatening conditions 3

Temperature Threshold

  • A core temperature of ≥38.2 degrees C is considered a fever in the postoperative period 2
  • Maintaining normothermia with active warming, such as warmed intravenous fluids, skin warming, and warm forced air, to keep the body temperature warmer than 36 °C is recommended to reduce the risk of surgical site infections 4

Clinical Significance

  • Postoperative fever is associated with adverse clinical outcomes, including increased organ dysfunction and risk of death 2
  • The magnitude of fever is a determinant of mortality, whereas an infectious etiology of fever may not be 2

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Fever in the postoperative patient.

Emergency medicine clinics of North America, 2013

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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