Which radiographic sign on a chest X-ray indicates a pleural effusion?

• A. Blunting of the costophrenic angle
• B. LobAR consolidation
• C. Hyperinflation of the lungs
• D. Pneumothorax

Answer: (A)

Pleural effusion shows up on a chest X-ray as blunting of the costophrenic angle. Fluid in the pleural space tends to pool at the base, dulling the sharp angle where the diaphragm meets the chest wall, especially when the patient is upright. Small amounts of fluid may be subtle and require lateral decubitus or other views to confirm, but the blunted angle is the classic radiographic clue.

Lobar consolidation would look like a dense patch in a specific lobe with possible air bronchograms, indicating infection or edema rather than fluid in the pleural space. Hyperinflation reflects increased lung volumes typical of obstructive disease. A pneumothorax appears as a visceral pleural line with a lack of lung markings beyond it, not as fluid blunting the diaphragmatic angles.