C44-21 Spontaneous Hemothorax Associated With Influenza A Infection

Abstract Background Hemothorax, defined by pleural fluid hematocrit ≥50% of peripheral blood, usually results from trauma, coagulopathy, or iatrogenic causes. Spontaneous hemothorax is rare and is typically associated with malignancy, vascular malformation, or connective tissue disease. We describe a unique case related to Influenza A infection. Case A 55-year-old man with hypertension, type 2 diabetes, and chronic liver disease presented with worsening left-sided chest discomfort and cough. He was recently diagnosed with bronchitis and later tested positive for Influenza A. Chest radiograph revealed a new large left pleural effusion with mediastinal shift. CTA thorax confirmed a large, intermediate-attenuation effusion with near-complete atelectasis. He was admitted for sepsis secondary to Influenza A and pleural effusion and started on broad-spectrum antibiotics. The bedside ultrasound revealed complex pleural fluid. A pigtail catheter was used to drain 1.4 liters of dark sanguineous fluid, with a hematocrit of 40% (serum 37%), confirming the diagnosis of hemothorax. The persistent effusion led to a uniportal video-assisted thoracoscopic surgery (VATS) for evacuation and partial decortication. During the procedure, there was no evidence of injury to the chest wall or lung parenchyma, and the vascular structures were intact, ruling out any iatrogenic injury. Two surgical chest tubes were placed during the operation and were removed on postoperative days 4 and 6. The patient underwent serial imaging due to ongoing increased work of breathing, which revealed a large left-sided pleural effusion with loculated components. A repeat chest CT showed a decrease in the effusion, with attenuation consistent with water. An interventional radiology (IR)-guided chest tube drained 340 mL in the first 24 hours. Fluid studies confirmed that the effusion was transudative. Only 20 mL of fluid was drained in the subsequent 24 hours, leading to the decision to remove the chest tube. The patient was discharged from the hospital after his chest X-ray findings had nearly resolved. Post-discharge chest X-rays indicated a persistent small left-sided effusion, which ultimately resolved two months after admission. Discussion This case highlights a rare spontaneous hemothorax associated with Influenza A. Possible mechanisms include virus-induced pleural inflammation or microvascular injury. Recognition is essential, as delayed diagnosis may lead to fibrothorax or empyema. Influenza-related hemothorax remains poorly described in the current literature. Conclusion Influenza A may be an underrecognized cause of spontaneous hemothorax and should be considered in patients presenting with pleural effusion during viral infection. This abstract is funded by: None