The pleural space refers to the layer of tissues that forms the gap between the lungs and the chest cavity. This area experiences an accumulation of pleural fluid, or pleural effusion. Transudate and exudate are the two factors that cause this process to occur. The former occurs from an imbalance between blood arteries and blood protein, which affects how fluids are transported, and the latter is caused by inflammation of the pleurae. The Pleural Fluid Routine examination determines which of the two causes contributed to the fluid buildup in the pleural space. It aids in the early detection of many blood-related issues.