PassFinals
Respiratory

Empyema (Pleural Infection)

Empyema is infected pleural fluid, usually arising from pneumonia and progressing from a simple parapneumonic effusion to loculated pus; antibiotics are essential but source control requires image-guided drainage, with intrapleural therapy or surgery when drainage is incomplete.

In a nutshell

Empyema is pleural infection, usually following pneumonia. Diagnose with ultrasound-guided pleural assessment and urgent pH/microbiology when fluid is not frank pus. Antibiotics plus image-guided chest drainage are the foundation; add tPA plus DNase for a residual loculated collection and involve thoracic surgery when source control fails or the lung is trapped.

Classic presentation

A patient treated for pneumonia has persistent fever, pleuritic pain, rising inflammatory markers and a septated effusion; aspiration is turbid with markedly low pH, so antibiotics and an image-guided chest drain are required.

Key points

  • Pleural infection ranges from a complicated parapneumonic effusion to frank pus; visible pus is not required for clinically important infection.
  • A markedly low pleural pH in non-purulent fluid is a drainage threshold; integrate intermediate results with LDH, glucose, imaging and fever.
  • Frank pus or positive pleural Gram stain/culture requires drainage as well as antibiotics.
  • Use small-bore image-guided drainage first; tPA plus DNase is for a residual loculated collection after drainage has ceased.
  • Persistent sepsis, trapped lung, bronchopleural fistula or a residual collection needs early pleural and thoracic-surgical review.

First-line investigation

Thoracic ultrasound with image-guided pleural aspiration for immediate pH, Gram stain, culture, glucose and LDH when the fluid is not obviously pus.

Management

Treat sepsis and start antibiotics

  • Stabilise sepsis, obtain cultures when safe and start community- or hospital-acquired pleural-infection antibiotics with specialist/BNF guidance; antibiotics do not replace source control.5,1,6

Sample and drain high-risk infection

  • Use ultrasound-guided aspiration and insert an image-guided small-bore drain for pus, positive microbiology or pleural pH at or below 7.2 when safe and accessible.1,4

Open loculations and review residual collections

  • If the drain stops with residual loculated fluid, discuss BTS-protocol intrapleural tPA plus DNase, consent for bleeding risk and review anticoagulation and coagulation status.3,1

Escalate to thoracic surgery when needed

  • Seek early surgical advice for persistent sepsis, failed drainage/intrapleural treatment, trapped lung, bronchopleural fistula or an organised pleural peel; individualise VATS or decortication timing.1,7,8

Reassess source control and recovery

  • Monitor drain function, inflammatory markers, renal function, oxygenation and imaging; reconsider malignancy, TB, PE, abscess or resistant infection when recovery is atypical and arrange pleural follow-up.1,8,2

Exam traps

  • Send pleural fluid pH immediately using correct blood-gas technique; contamination or delay can invalidate it.
  • Do not wait for frank pus if biochemical and clinical features indicate a high-risk complicated effusion.
  • Antibiotics alone do not provide source control for infected pleural fluid.
  • Initial drainage is usually image-guided and small-bore; routine immediate surgery is not required for every adult.
  • Use tPA plus DNase together for residual loculation; neither agent alone is the routine BTS regimen.
  • A lung abscess is intraparenchymal and rounded, whereas empyema is pleural and often lenticular or loculated.

Illustrations

Empyema on chest radiographA chest radiograph showing a pleural-based, lenticular opacity or loculated effusion forming an obtuse angle with the chest wall in a patient with pneumonia.James Heilman, MD, Wikimedia Commons · CC-BY-SA-3.0
Hydropneumothorax in pleural empyemaAxial chest CT showing a large right pleural air-fluid collection with pleural thickening and compression of adjacent lung, consistent with empyema and hydropneumothorax.Drriad, Wikimedia Commons · CC-BY-SA-3.0

Key sources

  1. British Thoracic Society, BTS Guideline for Pleural Disease (Current UK pleural-disease guideline covering pleural infection, fluid pH/LDH/glucose risk, initial small-bore drainage, intrapleural therapy, RAPID risk stratification and surgical escalation; published July 2023)Published 1 Jul 2023
  2. NICE NG250, Pneumonia: diagnosis and management (Current NICE pneumonia assessment, imaging, severity, antimicrobial, hospital and reassessment pathway; published 2 September 2025)Published 2 Sept 2025
  3. British Thoracic Society, Pleural Disease Online Appendix C4: Pleural infection intrapleural therapy (Current UK BTS intrapleural-treatment recommendations: tPA plus DNase combination, bleeding consent, reduced-dose specialist considerations and no routine monotherapy)Published 1 Jul 2023
  4. British Thoracic Society, Clinical Statement on Pleural Procedures (Current UK safety and image-guidance standards for aspiration, chest-drain insertion, intrapleural treatment and pleural procedures; published July 2023)Published 1 Jul 2023
  5. NICE NG253, Suspected sepsis in people aged 16 or over (Current adult sepsis recognition, investigation, antimicrobial, source-control, monitoring and escalation pathway; published 19 November 2025)Published 19 Nov 2025
  6. BNF, antibacterial drugs and intrapleural medicines (Current UK prescribing, contraindication, interaction, monitoring and patient-specific dosing reference; access may require subscription or institutional login)
  7. British Thoracic Society, Pleural Disease Online Appendices C5/C6: surgical approach and method (Current UK evidence review and recommendations informing VATS, thoracotomy, debridement and decortication decisions after medical drainage)Published 1 Jul 2023
  8. British Thoracic Society, Quality Standard for Pleural Disease (Current UK quality benchmark for adult pleural disease services, including pleural infection pathways; published May 2026)Published 1 May 2026

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.