A 32-year-old man is brought to the emergency department following a motor vehicle accident with multiple blunt injuries to the trunk and limbs. On examination, he has extensive bruising over the left flank and anterior chest wall. The attending physician suspects underlying rib fractures and potential pulmonary contusion. Which investigation is most appropriate to confirm the presence of pulmonary contusion?

Explanation

## Investigation of Choice for Pulmonary Contusion **Key Point:** HRCT chest is the gold standard investigation for detecting pulmonary contusion because it has superior sensitivity and specificity for identifying ground-glass opacities and consolidation patterns characteristic of contusion. ### Why HRCT is Superior Pulmonary contusion is a mechanical injury resulting in intra-alveolar and interstitial hemorrhage. While plain chest X-rays may show findings within 6–24 hours, HRCT can detect contusion within hours of injury and provides: - Better visualization of ground-glass opacities - Detection of small areas of consolidation - Assessment of extent and severity - Exclusion of other thoracic injuries (pneumothorax, hemothorax, mediastinal injury) ### Comparison of Investigations | Investigation | Sensitivity | Specificity | Timing | Clinical Use | | --- | --- | --- | --- | --- | | Plain CXR | 30–50% | Moderate | 6–24 hrs | Initial screening, cost-effective | | HRCT | 90–95% | High | Within hours | Gold standard, detailed assessment | | Ultrasound | Variable | Low | Immediate | Pneumothorax/hemothorax detection | | MRI | High | High | Delayed | Not first-line (time-consuming, contraindications) | **High-Yield:** In a trauma setting with suspected pulmonary contusion, HRCT is the investigation of choice because it: 1. Detects contusion earlier than plain radiography 2. Quantifies the extent of injury 3. Guides clinical management (mechanical ventilation, fluid restriction) 4. Helps prognosticate risk of acute respiratory distress syndrome (ARDS) **Clinical Pearl:** Pulmonary contusion can progress over 24–48 hours. Serial HRCT may be warranted in severe cases, but initial HRCT within the first few hours is most informative for detecting the injury and assessing severity. **Warning:** Plain chest X-rays may appear normal in the first 6 hours despite significant contusion; do not rely on CXR alone to exclude contusion in a high-clinical-suspicion case.