Abstract
Analysis of pleural fluid assists the diagnosis of intrathoracic
and systemic disorders that cause pleural effusions. Nearly 75%
of patients with pleural effusions gain either a definitive or pre-
sumptive diagnosis after a systematic analysis of pleural fluid.
The need for further diagnostic studies depends on whether
pleural fluid is classified by pleural fluid analysis as exudative or
transudative in nature. A Bayesian approach to discriminating
between exudative and transudative effusions increases diag-
nostic accuracy. Patients with exudative effusions may benefit
from pleural biopsy if the diagnosis remains uncertain after
thoracentesis. Infected pleural fluid or large, symptomatic effu-
sions benefit from chest tube drainage. Biopsy can be performed
by closed needle, image-guided needle, open surgical, and
thoracoscopic techniques. The diagnostic yield of each of these
procedures varies in different clinical settings. Chest tubes rep-
resent the primary technique for draining symptomatic effusions
and performing chemical pleurodesis. The type and caliber of
chest tube varies depending on the etiology and physical prop-
erties of the effusion.