While there is no universally accepted cutoff for the volume of blood loss required before surgery is indicated, generally accepted indications include more than 1500 mL of blood drained from a thoracostomy, bleeding rate of over 500mL/hr in the first hour followed by over 200 mL, hemodynamic instability, or the need for repeat blood transfusions. VATS is less invasive and cheaper than an open thoracotomy, and can reduce the length of hospital stay, but a thoracotomy may be preferred when hypovolemic shock is present, in order to watch bleeding. The procedure should ideally be performed within 72 hours of the injury as delay may increase the risk of complications. In clotted hemothorax, VATS is the generally preferred procedure to remove the clot, and is indicated if the hemothorax fills 1/3 or more of a hemithorax. The ideal time to remove a clot using VATS is at 48–96 hours, but can be attempted up to nine days after the injury. Other
Thoracentesis is no longer used in the treatment of hemothorax, although it may still be used to treat small hemothoraces. In catamenial hemothorax, the bleeding is typically self-limiting and mild. Most people with the condition are stable and can be treated with hormonal therapies. They are only partially effective. Surgical removal of the endometrial tissue may be necessary in recurrent cases. However, the disease frequently recurs. Resuscitation with intravenous fluids or with blood products may be required. In fulminant cases, transfusions may be administered before admission to the hospital.
Those with an abnormal accumulation of air within the pleural space (a pneumothorax) can bleed into the cavity, which occurs in about 5% of cases of spontaneous pneumothorax, especially when lung bullae rupture. The resulting combination of air and blood within the pleural space is known as a hemopneumothorax. Bone growth in exostosis can create sharp edges, which can result in hemothorax by damaging adjacent arteries. It can occur postpartum due to the change in thoracic pressure during labor. Vascular
Vascular causes of hemothorax include rupture of the descending aorta, in which case it initially involves the left pleural and mediastinal area due to the close vicinity of the pleural cavity. Rarely, a rupture of the thoracic aorta can result in a hemothorax, but the bleeding usually occurs in the pericardial space. Spontaneous tearing of blood vessels is more likely to occur in those with disorders that weaken blood vessels such as some forms of Ehlers-Danlos syndrome, disorders that lead to malformed blood vessels as seen in Rendu-Osler-Weber syndrome, or in bleeding disorders such as hemophilia and Glanzmann thromboastenia. Other rare causes of hemothorax include neurofibromatosis type 1 and extramedullary hematopoiesis. Catamenial
Rarely, hemothoraces can arise due to extrapelvic endometriosis, a condition in which tissue similar to the lining that normally covers the inside of the uterus forms in unusual locations outside the pelvis.