What condition is characterized by excess fluid in the pleural cavity?

The condition characterized by excess fluid in the pleural cavity is pleural effusion. This occurs when excess fluid collects between the layers of the pleura, which are the membranes surrounding the lungs and lining the thoracic cavity. Various underlying medical issues can lead to pleural effusion, including heart failure, infections, malignancies, and inflammatory diseases.

In contrast to pleural effusion, pneumothorax involves air in the pleural cavity, which can lead to lung collapse rather than fluid accumulation. Hemothorax specifically refers to the presence of blood in the pleural space, typically resulting from trauma or certain medical conditions. Empyema is a type of pleural effusion where the fluid is pus, often due to infection. Each of these conditions has distinct characteristics and causes, making pleural effusion the most appropriate term for the presence of excess fluid in the pleural cavity.