ABSTRACT
The radiographic appearance of pleural fluid is primarily influenced by patient positioning at the time of radiography. In an upright patient, free-flowing effusion of sufficient volume may produce a characteristic meniscus appearance. Intrafissural fluid or loculated collec tions may simulate mass lesions. Subpulmonic effusions may simulate diaphragmatic ele vation. In the supine patient, signs of significant pleural fluid collections may be subtle. The chest radiograph rarely reveals the specific cause or nature of pleural fluid, but some associated findings may help to narrow the range of diagnostic considerations. It is impor tant to be familiar with the various radiographic appearances of pleural effusion to allow detection and plan further diagnostic or therapeutic interventions.
