1. Post-operative fever

2. Febrile Surgical Patient
• Common
• Long list of differential diagnosis
• Understandable to equate fever with
infection
• Workup and therapy should be
individualized

3. What constitutes a fever?
•
•
•
•
Arbitrary
Temperature that raises concern
> 38oC
Increased metabolic rate 7% -15% / oC
– little morbidity aside of discomfort and
increased insensible fluid loss
• But risk of neurological injury if > 41 oC

4. Noninfectious Causes of
Fever
• Nosocomial infection unlikely in the first 48
hours after operation
• The most common cause of postoperative
fever is ATELECTASIS

5. Causes of post-op fever
• Non-infectious
• Infectious
– Device-related
– Not related to devices

6. Other Noninfectious Causes
•
•
•
•
•
•
Aspiration pneumonitis
Tissue ischaemia
Haematoma
Transfusion reaction
Gout/Pseudogout
Withdrawal of ethanol, sedatives, or
opioids
• Endocrine emergency
– thyrotoxicosis / adrenal insufficiency

7. Drug fever
•
•
•
•
•
Only 2 - 3% of all post-op fever
Usually due to hypersensitivity
Antibiotics most common
Diagnosed by exclusion
Fever often subsides after removal of
drugs
• Malignant hyperthermia
• Neuroleptic malignant syndrome

8. Haematological Fever
• Transfusion reaction
– passenger leukocytes leads to
alloimmunization to leukocyte-specific
antigens in the recipient
• Deep venous thrombosis
• Haematoma

9. Infectious Causes of Fever
• If operation is performed for control of an
infection, the fever is expected to settle
within 72 hrs
• New or persistent fever more than 3 days
after surgery should raise a strong
suspicion of persistent sepsis or a new
complication

10. Device-related infection
• Nosocomial infection often arise in
association with indwelling devices:
– IV drips
– ET-tube, tracheostomy tube, NG tube
– Urinary catheters
– Drains

11. Nosocomial Chest infection
• After 3rd day
• Risk factors:
– prolonged mechanical ventilation
– cardiothoracic, neurosurgical,
trauma operation
– major H&N or GI surgery
• purulent sputum, fever, high
WCC, and abnormal CXR

12. Urinary tract infection
• Seldom destabilizing
• Upper tract rare
• Most important risk factor
– duration of catheterization
• Indication of cath should be reviewed daily
• Remove at the earliest opportunity

13. Infection of vascular Access
• Central or peripheral lines
• Percutaneously placed catheter should
be removed
• Surgically placed catheter (e.g. Hickman
line) may be salvaged by antibiotics
(successful if Gram positive infection, not
likely if infected by pseudomonas or
fungus)

14. Nosocomial Infection not
related to Devices
• Wound infection
• Necrotizing fasciitis
• Pseudomembranous colitis
• Acalculus cholecystitis

15. Approach to Post-op Fever
• An individual approach is essential
• Unlikely diagnoses should not be pursued
until more common causes have been
excluded
• Important to differentiate whether the fever
is due to infection or just an inflammatory
response only

16. Approach to Post-op fever
according to time of onset

17. Day 1
• Most common: atelectasis
• Persistent sepsis if OT was done for
control of infection
• Rare causes:
•
•
•
•
thyroid crisis
transfusion reaction
drug fever
malignant hyperthermia / NMS

18. Day 2 - Day 3
• Infection related to indwelling device
– Drip site infection
– Chest infection / Sinusitis
– Bacterial cystitis
• Haematoma
• Tissue necrosis (e.g. flap)
• Gout / pseudogout

19. Day 4 - Day 5
• Wound infection
• Anastomotic leak
• Intra-abdominal abscess / collection
• Rare causes
– Antibiotics induced colitis
– Acute acalculous cholecystitis

20. Day 6 - Day 7
• All of the above and,
• Deep venous thrombosis
• Pulmonary embolism

21. Approach to Post-op Fever
• Careful review of history
– Premorbid condition
– Indication of surgery
– Nature of operation
• Physical examination
– Chart of vital signs
– Possible source of infection
• Consider culture of blood, sputum and urine
• CXR, +/- USG abdomen +/- CT scan
• Empiric antibiotics if necessary

22. Miss Emily Cheung (Ext 2679)
emilycheung@surgery.cuhk.edu.hk