Which type of pleural effusion is characterized by thin and clear fluid?

A pleural effusion characterized by thin and clear fluid is classified as a transudate. Transudate formations are typically due to systemic factors that alter the hydrostatic and oncotic pressures in the pleural space, such as congestive heart failure or cirrhosis. The fluid in transudates generally has a low protein content and low specific gravity, making it more translucent and less viscous.

In contrast, exudates generally contain higher levels of protein and tend to be cloudier due to the presence of cells and inflammatory mediators. Pneumonic effusions often result from infections and can lead to pus-filled (empyema) or turbid fluid, rather than clear fluid. Hemothorax refers to the accumulation of blood in the pleural space, which would present as bloody and not clear fluid.

Understanding these differences is crucial for diagnosing the underlying causes of pleural effusions and determining appropriate management strategies.