A simple pneumothorax is:

• A. Heals on its own without any treatment.
• B. Often has a nontraumatic cause.
• C. Is commonly caused by blunt chest trauma.
• D. Is caused by penetrating chest trauma.

Answer: (C)

A simple pneumothorax is air in the pleural space without tension or mediastinal shift. In the trauma setting, blunt chest trauma is a common mechanism that leads to this condition. The impact can cause rib fractures or lung tissue injury, allowing air to escape from the lung into the pleural space, creating a pneumothorax that may be small and self-limiting or require monitoring or drainage depending on size and symptoms. This makes blunt trauma a frequent and typical cause in many clinical scenarios.

While a small spontaneous pneumothorax (often in otherwise healthy young people) can occur without trauma, and penetrating chest trauma can also cause a pneumothorax, blunt trauma remains the most common traumatic mechanism in many cases. A pneumothorax that heals on its own is not guaranteed; management depends on size, symptoms, and ongoing risk, so saying it heals without any treatment isn’t universally accurate. And while nontraumatic causes exist, this option doesn’t best capture the most common traumatic mechanism highlighted in many exam contexts.