Evaluation of pleural fluid in patients with cirrhosis.

Although fluid analysis usually is the first step toward identifying the cause of pleural effusion in patients with cirrhosis and ascites, there are no available data on the reliability of this approach, therefore, we retrospectively evaluated hematologic and biochemical parameters from pleural fluid analysis in 21 patients with hepatic hydrothorax (with proven peritoneal-pleural communication) and 6 patients with primary pleural disease (2 with tuberculosis, 3 with parapneumonic effusion, and 1 with empyema). The criteria developed by Light were diagnostic of pleural "exudate" in only one of six patients with primary pleural disease, concentrations of leukocytes, total protein (TP), albumin, and lactic dehydrogenase (LDH) in both fluids were measured and pleural fluid-to-ascites ratios of these measurements were calculated. Only ratio values for leukocytes and TP were higher in the group of patients with primary pleural disease compared with those with hepatic hydrothorax. Ratio values for leukocytes and TP overlapped between both groups during baseline conditions and during episodes of spontaneous bacterial peritonitis and pleuritis. We conclude that pleural fluid analysis has limited diagnostic efficacy in the patient with cirrhosis. Data collected by other methods--clinical and radiologic--should assist in arriving at the correct diagnosis.