The undiagnosed pleural effusion

Clin Chest Med. 2006 Jun;27(2):309-19. doi: 10.1016/j.ccm.2005.12.002.


The most common causes for undiagnosed transudative effusions are congestive heart failure and hepatic hydrothorax. Pleural fluid N terminal pro-brain natriuretic peptide levels higher than 1500 pg/mL are virtually diagnostic of congestive heart failure. The most common causes for undiagnosed exudative pleural effusions are malignancy, pulmonary embolism, and tuberculosis. Clinical characteristics of patients with a malignant pleural effusion are symptoms for more than 1 month, absence of fever, blood-tinged pleural fluid, and CT findings suggestive of malignancy. Thoracoscopy is useful to establish the diagnosis of malignancy and tuberculosis.

Publication types

  • Review

MeSH terms

  • Bronchoscopy
  • Heart Failure / complications
  • Humans
  • Physical Examination
  • Pleural Effusion / diagnosis*
  • Thoracoscopy