Caption

Chest X-ray showing a pleural effusion, an introduction of fluid into the pleural cavity. The left lung field (right on image) is partly obscured by the accumulation of fluid. The pleural cavity is the space formed by the visceral & parietal pleura & is normally small as both membranes are in close contact. An introduction of fluid (pleural effusion) or gas separates the pleural surfaces and increases the volume of the pleural cavity.