A 28-year-old man is brought to the trauma centre 2 hours after a stab wound to the left anterior chest (5th intercostal space, midaxillary line). He is haemodynamically stable (BP 128/82 mmHg, HR 94/min), with normal breath sounds bilaterally and no external bleeding. On examination, there is a small puncture wound with minimal surrounding erythema. Bedside FAST is negative. Which investigation is most appropriate to exclude occult haemothorax and pneumothorax?

Explanation

## Clinical Context This is a **penetrating chest injury in a haemodynamically stable patient**. The goal is to detect occult pneumothorax and haemothorax that may not be clinically apparent. An upright posteroanterior (PA) chest X-ray is the gold standard initial imaging for stable patients with suspected pneumothorax or haemothorax. ## Key Point: **Upright PA chest X-ray is the investigation of choice for pneumothorax and haemothorax in stable patients.** It is sensitive, readily available, and allows detection of: - Air in the pleural space (pneumothorax) - Blood in the pleural space (haemothorax, seen as blunting of costophrenic angles or opacification) - Mediastinal shift (tension physiology) ## Advantages of Upright PA View | Feature | Upright PA | Supine Portable | |---------|-----------|----------------| | **Sensitivity for pneumothorax** | High (small apical air collections visible) | Low (air may not layer dependently) | | **Sensitivity for haemothorax** | High (fluid layers dependently) | Moderate (may appear as diffuse opacity) | | **Patient positioning** | Optimal for free air/fluid layering | Suboptimal; air rises anteriorly, fluid diffuses | | **Appropriate setting** | Stable patient, ED or radiology suite | Unstable patient, ICU, or bedside | ## High-Yield: - **Upright PA CXR** is the standard for stable patients with penetrating chest trauma. - **Supine portable CXR** is used only if the patient cannot be moved (haemodynamic instability, spinal precautions). - **CT chest** is reserved for haemodynamically stable patients with complex injuries or when CXR findings are equivocal. - **Ultrasound** (B-mode) can detect pneumothorax and haemothorax but is operator-dependent and not standard for initial evaluation in stable patients with penetrating trauma. ## Clinical Pearl: A **normal upright PA CXR does not exclude small pneumothorax**. If clinical suspicion is high, consider expiratory views or CT. However, in this stable patient with a small puncture wound and negative FAST, upright PA CXR is the appropriate next step.