PREVIEW
The causes of abnormal accumulation of fluid in the lungs are many and varied. Although analysis of pleural fluid uncovers the underlying problem in most cases, sometimes a definitive explanation is elusive. In this article, Drs Rubins and Colice review indications for thoracentesis and various other tests that can help resolve questions about pleural effusion. The authors also discuss diagnostic priorities for patients with exudative pleural effusions and suggest guidelines for understanding idiopathic effusions. An article by the same authors on practical management of pleural effusions will appear in an upcoming issue.