Empyema/Parapneumonic Effusion

Empyema/Parapneumonic Effusion


Exudative effusion, pH >7.2, culture and gram stain negative

Generally resolves with treatment of pneumonia and does not require modification of pneumonia therapy

Follow with serial Chest X-ray to significant improvement

Any parapneumonic effusion that is loculated, or culture positive, or pH < 7.2, but is not frankly purulent or gram stain positive

Consult Thoracic Surgery for drainage

Frank pus or organisms on gram stain in pleural fluid

May be culture negative

Consult Thoracic Surgery for drainage

One of:

  • Pleural protein to serum protein ratio > 0.5
  • Pleural LDH to serum ratio >0.6
  • Pleural LDH > 0.6 x the upper limit of normal for serum LDH

Management Pearls


Can reveal loculated fluid suggesting either empyema or complicated effusions

Can help to characterize location, and consistency of the fluid (i.e. echogenic fluid more likely empyema)

Can characterize the fluid location, loculation, and demonstrate thickened/enhancing pleura consistent with empyema or complicated effusions


All parapneumonic effusions >10mm depth should be sampled (smaller effusions generally resolve without intervention)

  • Positive gram stain or culture, or frank pus
  • Loculated collections, or thickened/enhancing pleura on imaging
  • Effusion causing significant respiratory compromise or sepsis
  • Large, fee-flowing effusions
  • Gram stain and aerobic/anaerobic culture
  • Cell count and differential
  • Chemistry - pH, total protein, LDH, glucose
  • ± TB/fungal depending on risk factors