The medical records were reviewed for demographic data, medical history, current medications, and clinical outcomes of each case. The procedure records were reviewed for laterality, sonographic appearance of the effusion, and volume removed during thoracentesis. Pleural fluid analysis included pH, total nucleated cell count with differential, total protein level, lactate dehydrogenase (LDH) level, glucose level, triglycerides level, amylase level, bacterial cultures, and cytology. Radiographic data were reviewed for laterality of the effusion and presence of ascites on CT imaging and to assess pulmonary or cardiac causes of the pleural effusion. Sonographic data (ie, abdominal ultrasonography) were reviewed for presence of ascites. Echocardiographic data, including left ventricular ejection fraction, presence of diastolic dysfunction, left atrial diameter, right ventricular systolic pressure, and intrapulmonary shunting, were also reviewed. Laboratory data, including brain natriuretic peptide (BNP) level, renal function, liver panel, coagulation profile, and CBC count, were reviewed, in addition to ascitic fluid analysis and cultures.