Pleural effusion is defined as

Pleural effusion is defined as

• A. A condition where air builds up in the pleural space
• B. A condition where fluid builds up in the pleural space between the lungs and chest wall
• C. A collapse of a portion of the lung
• D. Inflammation of the pleural membranes

Answer: (B)

Pleural effusion is the accumulation of fluid in the pleural space—the thin gap between the lungs and the chest wall. Normally this space contains only a small amount of lubricating fluid to reduce friction during breathing; when fluid builds up, it enlarges the space and can compress the lung. This definition sets it apart from a pneumothorax, where air collects in the pleural space; from atelectasis, which is the collapse or collapse tendency of lung tissue; and from pleuritis, which is inflammation of the pleural membranes and not specifically defined by fluid accumulation. Clinically, a fluid-filled pleural space can lead to dyspnea and signs like reduced breath sounds and dullness to percussion, depending on the amount of fluid.

Pleural effusion is the accumulation of fluid in the pleural space—the thin gap between the lungs and the chest wall. Normally this space contains only a small amount of lubricating fluid to reduce friction during breathing; when fluid builds up, it enlarges the space and can compress the lung. This definition sets it apart from a pneumothorax, where air collects in the pleural space; from atelectasis, which is the collapse or collapse tendency of lung tissue; and from pleuritis, which is inflammation of the pleural membranes and not specifically defined by fluid accumulation. Clinically, a fluid-filled pleural space can lead to dyspnea and signs like reduced breath sounds and dullness to percussion, depending on the amount of fluid.