What term is used for blood accumulated in the pleural space?

The term used for blood that has accumulated in the pleural space is "hemothorax." This condition typically occurs as a result of trauma or injury to the chest, leading to bleeding from the blood vessels into the pleural cavity. The presence of blood in this space can hinder normal respiratory function and may require medical intervention, such as drainage or surgery, to remove the blood and address the underlying cause.

The other terms indicate different types of pleural effusions, which involve fluid other than blood. A pneumothorax refers to the presence of air or gas in the pleural space, which can cause lung collapse. Hydrothorax describes an accumulation of serous fluid, often related to congestive heart failure or other conditions that cause fluid overload. Chylothorax involves the presence of lymphatic fluid, typically resulting from trauma or obstruction of the thoracic duct. Each of these conditions affects the pleural space differently, making "hemothorax" the specific term for the presence of blood.