What are the British Thoracic Society (BTS) guidelines for the investigation of a unilateral pleural effusion?

Updated: Dec 28, 2018
  • Author: Kamran Boka, MD, MS; Chief Editor: Guy W Soo Hoo, MD, MPH  more...
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Answer

The key British Thoracic Society guideline recommendations for the investigation of a unilateral pleural effusion include the following [61] :

  • Bedside ultrasound guidance improves success rate, reduces complications (including pneumothorax), significantly increases the likelihood of successful pleural fluid aspiration, and reduces the risk of organ puncture (level B).
  • Ultrasound detects pleural fluid septations with greater sensitivity than CT scanning (level C).
  • Pleural fluid should always be sent for protein, lactate dehydrogenase (LDH), Gram stain, cytology and microbiological culture (level C).
  • Light’s criteria should be used to distinguish between a pleural fluid exudate and transudate. In order to apply Light’s criteria, the total protein and LDH values should be measured in both blood and pleural fluid (level B).
  • Pleural fluid cell proportions are helpful in narrowing the differential diagnosis but are not disease-specific (level C).
  • Pleural malignancy, cardiac failure, and tuberculosis are common specific causes of lymphocyte-predominant effusions (level C).
  • In nonpurulent effusions, when pleural infection is suspected, pleural fluid pH should be measured providing that appropriate collection technique can be observed and a blood gas analyzer is available (level B).
  • Inclusion of air or local anaesthetic in samples should be avoided as they may significantly alter the pH results (level B).
  • Tube drainage is required in a parapneumonic effusion with a pH of less than7.2 (level B).
  • Malignant effusions can be diagnosed based on pleural fluid cytology results in about 60% of cases (level B).
  • Immunocytochemistry should be used to differentiate between malignant cell types and can be very important in guiding oncological therapy (level C).
  • CT scans should be performed with contrast enhancement and before complete drainage of pleural fluid (level C).
  • CT scans can be useful in distinguishing malignant from benign pleural thickening and should be performed in all undiagnosed exudative pleural effusions (level C).
  • A CT scan should be requested for complicated pleural infection when initial tube drainage has been unsuccessful and surgery is to be considered (level C).
  • When investigating an undiagnosed effusion in which malignancy is suspected and areas of pleural nodularity are shown on contrast-enhanced CT, an image-guided cutting needle is the percutaneous pleural biopsy method of choice (level A).
  • Thoracoscopy is the investigation of choice in exudative pleural effusions in which a diagnostic pleural aspiration is inconclusive and malignancy is suspected (level C).
  • Routine diagnostic bronchoscopy should not be performed for undiagnosed pleural effusion (level C).
  • Bronchoscopy should be considered in the presence of hemoptysis or clinical or radiographic features suggestive of bronchial obstruction (level C).

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