A patient has dyspnea and dullness to percussion at the left base with decreased breath sounds. Which imaging modality best confirms a pleural effusion?

• A. Ultrasound of the chest
• B. Chest X-ray
• C. CT scan
• D. MRI

Answer: (A)

Ultrasound of the chest is best for confirming a pleural effusion because it detects even small amounts of fluid between the pleural layers with high sensitivity and can be performed at the bedside. It provides real-time visualization of the fluid, helps estimate its volume, and can distinguish fluid from surrounding tissue or consolidation. Importantly, it guides thoracentesis, allowing safe needle placement and reducing the risk of complications like pneumothorax. While chest X-ray can show effusions, it may miss small ones and is limited by patient positioning. CT offers more detail but isn’t the first-line confirmatory test due to higher cost, radiation, and practicality. MRI is not typically used for this purpose.