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Pleural Effusion

BTS Guideline for Pleural Disease. Published: Jul 2023.

Guidelines

To confirm pleural effusion:
  • 1st line: chest X-ray or thoracic ultrasound
  • Gold standard: CT chest

To investigation the underlying cause:
  • Ultrasound guided thoracentesis
  • Send pleural fluid for
    • Biochemistry: protein, LDH, glucose, pH
    • Microbiology: gram stain, culture
    • Cytology
 

The Light's criteria is used to distinguish between exudative and transudative causes of pleural effusion.

Exudative cause of pleural effusion is likely if at least 1 of the following:
  • Pleural fluid: serum protein ratio >0.5
  • Pleural fluid: serum LDH ratio >0.6
  • Pleural fluid LDH >2/3 the upper limit of serum LDH normal value

Treatment is indicated if symptomatic:
  • 1st line: pleural fluid aspiration (thoracentesis)
  • 2nd line: chest drain insertion

Pleural infection and malignant pleural effusion has distinctive management approaches. 
 

Pleural infection (term used by BTS) includes:
  • Empyema - presence of pus in the pleural space
  • Complicated parapneumonic effusion - no pus but infection spread to the pleural space

Note that treatment is indicated in ALL patients with pleural infection:
  • 1st line (all patients): antibiotics + chest drain insertion
  • 2nd line: intrapleural enzyme therapy (thrombolytic therapy + DNase)
  • 3rd line: surgical intervention
    • VATSVideo-assisted thoracoscopic surgery is generally preferred
    • Open thoracotomy typically reserved for advanced disease or failed VATSVideo-assisted thoracoscopic surgery

Treatment is only indicated if symptomatic:
  • Expandable lung: indwelling pleural catheter or chemical pleurodesis 
  • Non-expandable lung: indwelling pleural catheter

References

Author: Stella Panou
Reviewer:
Last edited: 30/07/25