What is the typical chest X-ray finding for pleural effusion?

• A. Blunting of costophrenic angles
• B. Hyperlucent lung fields
• C. Lateral rib fracture
• D. Elevated hemidiaphragm without effusion

Answer: (A)

Pleural effusion on a chest X-ray most characteristically shows blunting of the costophrenic angles. Fluid in the pleural space collects at the lung bases when you’re upright, fading the sharp angle where the diaphragm meets the rib cage. Small effusions may cause only subtle blunting, while larger ones can obscure the lateral costophrenic sulcus and produce a meniscus sign as the fluid layers due to gravity. In cases where fluid is tiny or the patient can’t stand, a lateral decubitus view or other imaging can help reveal the layering fluid. Other options don’t fit this typical pattern: hyperlucent fields suggest air-related issues like pneumothorax or emphysema, a lateral rib fracture is a bone injury, and an elevated hemidiaphragm without effusion lacks the fluid layering that blunts the costophrenic angles.