Pleural fluid can dilute hemothoraces in as low as 3–4 days. The red blood cells in the effusion spontaneously break down. Distinguishing the pleural fluid from blood by colour is impossible when the hematocrit value is over 5%. For these reasons, even if there is a hematocrit value under 50%, further investigations can be done in order to figure out if there is a source of bleeding. Hematocrit can be roughly calculated by dividing the red blood cell count of the pleural fluid by 100,000. Thoracentesis is the test most commonly used to diagnose a hemothorax in animals. Hemothorax can itself be a rare complication of thoracentesis if the intercostal artery is punctured. Treatment
The treatment of a hemothorax depends largely on the extent of bleeding. While small hemothoraces may require little in the way of treatment, larger hemothoraces may require fluid resuscitation to replace the blood that has been lost, drainage of the blood within the pleural space using a procedure known as a tube thoracostomy, and potentially surgery in the form of a thoracotomy or video-assisted thoracoscopic surgery (VATS) to prevent further bleeding. Occasionally, transcatheter arterial embolization may be used to stop ongoing arterial bleeding. Additional treatment options include antibiotics to reduce the risk of infection and fibrinolytic therapy to break down clotted blood within the pleural space. Thoracostomy
Blood in the cavity can be removed by inserting a drain (chest tube) in a procedure called a tube thoracostomy.
This accumulation of fluid in the pleural cavity is called pleural effusion. Pleural effusions are given specific names depending on the nature of the fluid: hydrothorax for serous fluid, pyothorax for pus, hemothorax for blood, and urinothorax for urine. Signs and symptoms
Signs and symptoms include anxiety, rapid breathing, restlessness, shock, and pale, cool, clammy skin. When the affected area is percussed, a dull feeling may be observed. Neck veins may be flat and breathing sounds reduced. It can also cause a collapsed lung (atelectasis). Massive hemothorax, often defined as over 1.5 liters of blood initially when an intercostal drain is placed, or a bleeding rate greater than .2 liters/hr, can result in shock with two causes: massive bleeding resulting from hypovolemic shock, and venous pressure from the retained blood, impairing blood flow. Causes
Hemothoraces are classified in three broad categories according to the cause and in order of frequency: traumatic, iatrogenic, or nontraumatic. All three categories have the potential to affect major arteries and result in death by blood loss. Traumatic
Hemothorax is most often caused by blunt or penetrating trauma to the chest. In blunt traumatic cases, hemothorax typically occurs when rib fracture damages the intercostal vessels or the intraparenchymal pulmonary vessel, while in penetrating trauma, hemothorax occurs due to injuries directly affecting blood vessels in the thoracic wall, lung parenchyma, or the heart. If large blood vessels such as the aorta are damaged, the blood loss can be massive.