In blunt thoracic trauma, which injury is considered a hidden thoracic injury?

• A. Myocardial contusion
• B. Rib fracture
• C. Pneumothorax
• D. Hemothorax

Answer: (A)

In blunt chest trauma, some injuries are obvious on initial exam or imaging, while others can be occult and not immediately apparent. Myocardial contusion is bruising of the heart muscle from the impact and can be silent at first—ECG changes or troponin elevations may be delayed or subtle. Because the heart injury may not be evident right away but can lead to arrhythmias, conduction abnormalities, or heart failure, it’s considered a hidden thoracic injury. In contrast, rib fractures and pneumothorax or hemothorax are usually detectable with imaging or examination, so they’re not hidden injuries.