Intended for healthcare professionals

Clinical Review

The modern diagnosis and management of pleural effusions

BMJ 2015; 351 doi: (Published 08 September 2015) Cite this as: BMJ 2015;351:h4520
  1. Rahul Bhatnagar, academic clinical lecturer1,
  2. Nick Maskell, professor of respiratory medicine2
  1. 1Academic Respiratory Unit, University of Bristol, Southmead Hospital, Bristol BS10 5NB, UK
  2. 2North Bristol Lung Centre, Southmead Hospital, North Bristol NHS Trust, Bristol, UK
  1. Correspondence to R Bhatnagar Rahul.Bhatnagar{at}

The bottom line

  • Pleural effusions are common and may be caused by a variety of underlying illnesses

  • An undiagnosed unilateral pleural effusion, without a history suggestive of acute infection, should be considered malignant until proved otherwise

  • Bilateral effusions are usually due to cardiac, renal, or hepatic impairment—treatment of the cause will usually improve effusions without the need for intervention

  • Chest radiography and computed tomography are vital early investigations in the diagnosis of pleural effusions

  • Both the safety and the success of pleural procedures are improved by the use of thoracic ultrasonography to guide needle placement

  • There is an increasing drive to diagnose and manage effusions in the outpatient setting, with pleural clinics and medical thoracoscopy streamlining the diagnostic pathway

  • Indwelling pleural catheters can now allow many patients with recurrent effusions to be managed at home

A pleural effusion describes an excess of fluid in the pleural cavity, usually resulting from an imbalance in the normal rate of pleural fluid production or absorption, or both. Pleural effusions are common, with an estimated 1-1.5 million new cases in the United States and 200 000-250 000 in the United Kingdom each year.1 This review describes how pleural effusions may be investigated and treated in the community and secondary care, with a particular focus on the emerging phenomenon of ambulatory management.

Sources and selection criteria

We searched through PubMed, Embase, Medline, and the Cochrane database of systematic reviews from inception to April 2015 using the primary search terms “pleural effusion” and “indwelling pleural catheter”. We included abstracts published in English and related to adults. Priority was given to randomised controlled trials and meta-analyses, although citations from case series and retrospective studies have been included where appropriate. Further information was obtained from our personal libraries, trial registration databases (such as, and conference proceedings where necessary.

What are the most common causes of pleural effusions?

More than 50 causes of pleural effusions …

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