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Pleural effusion

Evidence last reviewed: 22 Apr 2026
Topic last updated: 21 May 2026

Summary

Definition

History and exam

Key diagnostic factors

  • congestive heart failure, pneumonia, and malignancy
  • dyspnea
  • dullness to percussion
Full details

Other diagnostic factors

  • pleuritic chest pain
  • cough
  • absent or decreased breath sounds
  • decreased or absent tactile fremitus
Full details

Risk factors

  • congestive heart failure
  • pneumonia
  • malignancy
  • pulmonary embolism
  • recent coronary artery bypass graft surgery
  • recent myocardial infarction
  • occupational lung disease
  • rheumatoid arthritis
  • systemic lupus erythematosus
  • renal failure
  • drug-induced pleural effusion
  • recent ovarian stimulation treatment
  • trauma
Full details

Diagnostic tests

1st tests to order

  • posteroanterior and lateral chest x-ray
  • pleural ultrasound
  • LDH and protein in pleural fluid and serum
  • red blood cell count in pleural fluid
  • WBC count and differential of pleural fluid
  • cytology of pleural fluid
  • culture of pleural fluid
  • pH of pleural fluid
  • glucose in pleural fluid
  • protein gradient
  • CBC
  • C-reactive protein (CRP)
  • blood culture
  • sputum Gram stain and culture
  • N-terminal pro-brain natriuretic peptide (NT-pro-BNP) in pleural fluid and serum
Full details

Tests to consider

  • pleural fluid cholesterol level
  • thoracic CT scan
  • thoracic MRI
  • amylase in pleural fluid
  • adenosine deaminase (ADA) level in pleural fluid
  • lipid analysis of pleural fluid
  • antinuclear antibody (ANA) analysis of pleural fluid
  • thoracoscopy
  • bronchoscopy
  • pleural biopsy
  • interferon-gamma in pleural fluid and real-time polymerase chain reaction of pleural fluid
  • procalcitonin
Full details

Emerging tests

  • tumor markers

Treatment algorithm

ACUTE

congestive heart failure

infective

malignant: poor performance status or limited lifespan (Karnofsky score ≤30% or ECOG score of ≥2)

malignant: good performance status (Karnofsky score >30% or ECOG score of 0 or 1)

ONGOING

persistent empyema despite chest tube

recurrent symptomatic malignant effusions

recurrent benign effusion

Contributors

Authors

Orhan Orhan, MBBS, BSc, FRCP, SFHEA, MSc

Consultant Respiratory Physician

Chelsea and Westminster Hospital NHS Foundation Trust

London

UK

Disclosures

OO declares that he has no competing interests.

Acknowledgements

Dr Orhan Orhan would like to gratefully acknowledge Drs Clare Ross, Philip W. Ind, Anob M. Chakrabarti, Richard Light, Amber Degryse, Rachel J. Davies, and Peter M. George, previous contributors to this topic.

Disclosures

RL received speaking fees provided by Cardinal Health; owned stock in Denver Biomaterials until it was purchased by Cardinal Health; received fees for consulting from Denver Biomaterials; and is an author of references cited in this topic. CR, PWI, AMC, AD, RJD, and PMG declare that they have no competing interests.

Peer reviewers

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

UK

Disclosures

YCGL declares that he has no competing interests.

Clare Hooper, MBBS

Pleural Research Registrar

North Bristol Lung Centre

Southmead Hospital

Westbury on Trym

Bristol

UK

Disclosures

CH declares that she has no competing interests.

Benjamin DeMarco, MD

Assistant Professor of Medicine

Division of Pulmonary and Critical Care Medicine

University of North Carolina School of Medicine

Chapel Hill

NC

Disclosures

BD declares that he has no competing interests.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

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

Feller-Kopman D, Light R. Pleural Disease. N Engl J Med. 2018 Feb 22;378(8):740-751.

Roberts ME, Rahman NM, Maskell NA, et al. British Thoracic Society Guideline for pleural disease. Thorax. 2023 Jul;78(suppl 3):s1-42.Full text

Sundaralingam A, Grabczak EM, Burra P, et al. ERS statement on benign pleural effusions in adults. Eur Respir J. 2024 Dec;64(6):2302307.Full text  Abstract

Expert Panel on Thoracic Imaging, Morris MF, Henry TS, et al. ACR Appropriateness Criteria® workup of pleural effusion or pleural Disease. J Am Coll Radiol. 2024 Jun;21(6):S343-52. Abstract

Bibby AC, Dorn P, Psallidas I, et al. ERS/EACTS statement on the management of malignant pleural effusions. Eur Respir J. 2018 Jul;52(1):1800349.Full text  Abstract

Feller-Kopman DJ, Reddy CB, DeCamp MM, et al. Management of malignant pleural effusions. An official ATS/STS/STR clinical practice guideline. Am J Respir Crit Care Med. 2018 Oct 1;198(7):839-49.Full text  Abstract

Reference articles

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

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    • ACR appropriateness criteria: chronic dyspnea-noncardiovascular origin
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  • Patient information

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