Final answer:
Hemothorax is the term used to describe blood in the pleural space. It can be caused by different factors and requires drainage and treatment of the underlying cause.
Step-by-step explanation:
Blood in the pleural space is called hemothorax. It refers to the accumulation of blood in the pleural cavity, the thin space between the visceral and parietal pleura in the thorax. Hemothorax can occur due to various causes, including chest trauma, lung or blood vessel rupture, or certain medical conditions. Treatment typically involves draining the blood from the pleural space and addressing the underlying cause.