Abstract
Hemothorax is a rare and potentially fatal condition characterized by pleural effusion containing over 50% of the patient's hematocrit. A massive hemothorax involves blood loss exceeding 1.5 L. Common causes include chest trauma, invasive thoracic procedures, anticoagulant medications, vascular anomalies, malignancies, and hematologic abnormalities. Spontaneous hemothorax may be seen in conjunction with pulmonary infarction and spontaneous pneumothorax. Anticoagulation is a key therapeutic strategy for certain thromboembolic events, such as pulmonary embolism. Historically, these events were treated with vitamin K antagonists (VKAs), which have demonstrated variable plasma concentrations and an increased risk of hemorrhage. With the advent of direct oral anticoagulants (DOACs), treatment has become as effective as VKAs while significantly reducing the risk of hemorrhage. However, some researchers have speculated that hemorrhagic complications in certain cases could be worse with DOACs than with VKAs. In the case presented here, we identified a genuine association between the use of rivaroxaban and spontaneous hemothorax following the initiation of treatment for pulmonary embolism.