Empyema

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 23 Apr 2025

Last updated: 07 Mar 2024

Empyema is defined as the presence of pus in the pleural space.

Risk factors include pneumonia, iatrogenic intervention in the pleural space, diabetes, and alcohol abuse.

In patients with symptoms and signs of infection and a significant pleural effusion, thoracentesis (pleural aspiration) must be performed urgently.

If empyema or a complicated parapneumonic effusion is diagnosed, a chest drain must be inserted urgently.

A prolonged course of antibiotics is also required.

If patients do not improve with antibiotics and drainage of the pleural space, surgery or intrapleural enzyme therapy should be considered.

Mortality is approximately 15% to 20%.

Definition

Empyema is defined as the presence of frank pus in the pleural space. Parapneumonic effusions are effusions caused by an underlying pneumonia. A simple parapneumonic effusion is not infected, whereas a complicated parapneumonic effusion develops once infection has spread to the pleural space. These three conditions represent a spectrum of pleural inflammation in response to infection, ranging from a simple parapneumonic effusion to empyema.

History and exam

Key diagnostic factors

recent pneumonia
constitutional symptoms
pyrexia and rigors
dullness to percussion
reduced breath sounds and reduced vocal resonance
signs of sepsis

Full details

Other diagnostic factors

subacute presentation
productive cough
pleuritic chest pain
dyspnea
recent instrumentation of the pleural space

Full details

Risk factors

pneumonia
iatrogenic interventions in the pleural space
thoracic trauma
immunocompromised state
comorbid lung disease
male sex
older or young age

Full details

Diagnostic tests

1st tests to order

blood cultures
CRP
WBC count
metabolic panel
chest x-ray
thoracic ultrasound
thoracentesis: pleural fluid appearance
thoracentesis: pleural fluid odor
thoracentesis: pleural fluid pH
thoracentesis: pleural fluid total protein concentration
thoracentesis: pleural fluid LDH level
thoracentesis: pleural fluid glucose concentration
thoracentesis: pleural fluid white cell differential
thoracentesis: pleural fluid microscopy, culture, and sensitivity

Full details

Tests to consider

contrast-enhanced thoracic CT
MRI of thorax
PET scan
pleural fluid polymerase chain reaction (PCR)

Full details

Treatment algorithm

INITIAL

adults (culture results pending)

children (culture results pending)

ACUTE

adults (culture results available)

children (culture results available)

Contributors

Authors

Christopher Kapp, MD

Assistant Professor of Medicine, Interventional Pulmonologist

Division of Pulmonary and Critical Care, Section of Interventional Pulmonary

Northwestern Memorial Hospital

Chicago

Disclosures

CK declares that he has no competing interests.

Jeremy Kim, MD

Instructor of Medicine, Interventional Pulmonology Fellow

Division of Pulmonary and Critical Care, Section of Interventional Pulmonary

Northwestern Memorial Hospital

Chicago

Disclosures

JK declares that he has no competing interests.

Acknowledgements

Dr Christopher Kapp and Dr Jeremy Kim would like to gratefully acknowledge Dr Athanasia D. Pataka, Dr Renata L. Riha, Dr Najib M. Rahman, and Dr Eleanor K. Mishra, previous contributors to this topic. ADP, RLR, and EKM declare that they have no competing interests. NMR declares that Roche UK supplied clinical trial supplies and funding for the MIST2 trial that he conducted.

Peer reviewers

Steven Sahn, MD

Professor of Medicine and Director

Division of Pulmonary/Critical Care/Allergy/Sleep Medicine

Medical University of South Carolina

Charleston

Disclosures

SS declares that he has no competing interests.

Nicholas Maskell, MD

Senior Lecturer and Consultant Physician

North Bristol Lung Centre

Southmead Hospital

Bristol

Disclosures

NM declares that he has no competing interests.

Y.C. Gary Lee, MBChB, PhD, FCCP, FRACP

Consultant Chest Physician and Senior Lecturer

Oxford Centre for Respiratory Medicine and University of Oxford Churchill Hospital

Oxford

Disclosures

YCGL declares that he has no competing interests.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Shen KR, Bribriesco A, Crabtree T, et al. The American Association for Thoracic Surgery consensus guidelines for the management of empyema. J Thorac Cardiovasc Surg. 2017 Jun;153(6):e129-46.Full text Abstract

Maskell NA, Davies CW, Nunn AJ, et al. UK controlled trial of intrapleural streptokinase for pleural infection. N Engl J Med. 2005 Mar 3;352(9):865-74.Full text Abstract

Canadian Paediatric Society. Paediatric complicated pneumonia: diagnosis and management of empyema. Jan 2024 [internet publication].Full text

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials
- Pneumonia
- Uncomplicated parapneumonic effusion
- Lung abscess
More Differentials
Guidelines
- ACR Appropriateness Criteria: radiologic management of infected fluid collections
- The American Association for Thoracic Surgery consensus guidelines for the management of empyema
More Guidelines
Patient information
Pneumonia
More Patient information
Videos
Pleural aspiration animated demonstration
Insertion of intercostal drain, Seldinger technique: animated demonstration
More videos
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Empyema

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic tests

1st tests to order

Tests to consider

Treatment algorithm

adults (culture results pending)

children (culture results pending)

adults (culture results available)

children (culture results available)

Contributors

Authors

Christopher Kapp, MD

Disclosures

Jeremy Kim, MD

Disclosures

Acknowledgements

Peer reviewers

Steven Sahn, MD

Disclosures

Nicholas Maskell, MD

Disclosures

Y.C. Gary Lee, MBChB, PhD, FCCP, FRACP

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials

Guidelines

Patient information

Videos

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice