Hemothorax is the presence of blood within the pleural cavity, defined by a hematocrit of pleural fluid >50% of peripheral blood. Etiologies include blunt and penetrating chest trauma (most common), iatrogenic from central venous catheter or thoracentesis, vascular causes (thoracic aortic dissection or rupture, arteriovenous malformation), anticoagulation, malignancy with pleural metastases, and pulmonary infarction. Massive hemothorax (>1500 mL initial output or ongoing >200 mL/hr for 4 hours) is life-threatening from hypovolemic shock and lung compression.
Patients present with dyspnea, tachycardia, hypotension in significant blood loss, dullness to percussion, and decreased breath sounds. In trauma, associated injuries (rib fractures, lung contusion, aortic injury, diaphragmatic rupture) are common. Diagnostic studies include upright chest radiograph (blunting >250 mL, opacification), bedside ultrasound (FAST exam in trauma), and CT angiography for hemodynamically stable patients to localize bleeding source, assess injury extent, and guide management.
Resuscitation with two large-bore IV access, blood products, and tranexamic acid in trauma is followed by large-bore (28-36 Fr) chest tube placement to evacuate blood, monitor output, and prevent retained hemothorax. Indications for thoracotomy include initial output >1500 mL, ongoing output >200 mL/hr for 4 hours, hemodynamic instability after drainage, or vascular injury on imaging. Video-assisted thoracoscopic surgery (VATS) is the procedure of choice for evacuation of retained hemothorax (>500 mL or >1/3 hemithorax after 72 hours) to prevent empyema and trapped lung. Reverse anticoagulation when applicable.