ABSTRACT
Hemothorax is defined as accumulation of a significant amount of blood in the pleural space. By pure visualization of pleural fluid, it is clinically difficult to judge the amount of blood, and usually this is overestimated (1). For a hemothorax, the hematocrit of the pleural fluid should be at least 50% that of the peripheral blood (2). A massive hemothorax is defined as the accumulation of more than 800 mL of blood (3). It should be noted that the pleural space can contain up to 6 L of blood (4). On chest x-ray the amount is considered significant when there is opacification of either diaphragmatic dome or when the depth of blood on the lateral decubitus film exceeds 2 cm at its deepest point (5). In one prospective study on the value of the computed tomography (CT) in blunt chest trauma, hemothorax was defined on CT scan as an intrapleural collection of fluid equivalent to blood (30-100 Hounsfield units) with a thickness of more than 10 mm (6). Immediate insertion of a chest drain is the best prophylaxis against pleural space complications (4). The latter, listed in Table 1, result from an inadequately drained hemothorax.
