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...
  • Print

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).

Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!