Causes of Massive Hemothorax
The most common cause of massive hemothorax is injury to the intercostal artery, which can lead to rapid and life-threatening bleeding into the pleural space. 1, 2
Definition and Clinical Significance
Massive hemothorax is defined as the accumulation of blood in the pleural space that can threaten life through:
- Asphyxiation
- Exsanguination
- Rapid hemodynamic compromise
Clinically, massive hemothorax is often quantified as:
- At least 200 mL of blood in 24 hours 1
- Or 1,500-2,000 mL of blood accumulation in the pleural space
Major Causes of Massive Hemothorax
1. Vascular Injuries (Most Common)
Intercostal artery injury - most frequent cause 1, 2
- Can occur from trauma, procedures (thoracentesis), or spontaneously
- Located along the inferior border of each rib, making them vulnerable during chest trauma
Hilar vessel injury - second most common cause 1
- Involves major pulmonary vessels at the hilum
- Often associated with severe trauma or iatrogenic injury
- Carries high mortality due to rapid blood loss
Other vascular sources:
2. Lung Parenchymal Injury
- Less common primary cause of massive hemothorax
- Usually contributes to hemothorax when combined with vascular injury
- Typically self-limiting unless major vessels are involved
Etiologies by Mechanism
Traumatic Causes
- Penetrating trauma (stab wounds, gunshot wounds)
- Blunt trauma (rib fractures with intercostal vessel injury)
- Iatrogenic causes:
Non-traumatic Causes
- Spontaneous bleeding:
- Malignancy (primary or metastatic)
- Pulmonary infarction
Clinical Presentation and Diagnosis
Key symptoms and signs include:
- Chest pain and shortness of breath
- Shock symptoms in severe cases
- Attenuated or absent breath sounds on the affected side
- Percussion dullness
Diagnostic approach:
- Chest radiography - shows opacification of hemithorax
- Ultrasound - highly sensitive for detecting pleural fluid
- CT scan - identifies specific source of bleeding when patient is stable
Management Considerations
For massive hemothorax:
- Immediate tube thoracostomy (chest tube placement) in the 4th/5th intercostal space in the midaxillary line 1
- Volume resuscitation and blood product replacement
- Consideration for surgical intervention or angiographic embolization for ongoing bleeding
- Monitoring for complications including empyema and trapped lung
Conclusion
When evaluating the options presented in the question:
- A. Subcostal artery - not a primary cause of massive hemothorax
- B. Hilar vessel - significant cause but not the most common
- C. Lung parenchyma - rarely the sole cause of massive hemothorax
The intercostal artery (not listed as an option) is the most common source of massive hemothorax based on current evidence, with hilar vessels being the second most common source.