What does a chest X-ray typically show for a pleural effusion?

A pleural effusion, which occurs when excess fluid accumulates in the pleural cavity, is typically characterized on a chest X-ray by the blunting of the costophrenic angle. This blunting occurs because the fluid fills the pleural space and obscures the sharp angle formed between the diaphragm and the rib cage on the X-ray.

As fluid accumulates, it will naturally settle in the most dependent areas of the pleural space, which are the costophrenic angles. This highlights the significance of recognizing the alterations in the costophrenic angles as a key imaging sign of pleural effusions. In a normal X-ray, these angles are sharp; hence, their blunting indicates the presence of pleural fluid.

The other options do not correctly represent findings consistent with pleural effusions. Consolidation in the lung would be indicative of pneumonia or other lung pathologies. A pneumothorax sign would show collapsed lung spaces and is unrelated to fluid accumulation. Interstitial edema refers to fluid within the lung interstitium, often associated with conditions such as congestive heart failure, rather than fluid in the pleural space. Thus, recognizing blunted costophrenic angles on X-ray is crucial for diagnosing pleural