On chest radiograph, which finding suggests pleural effusion?

On chest radiograph, which finding suggests pleural effusion?

• A. Blunted costophrenic angle
• B. Lobar consolidation
• C. Hyperinflation
• D. Mediastinal shift

Answer: (A)

Fluid in the pleural space produces a recognizable change on chest X-ray, with the earliest and most specific clue being blunting of the costophrenic angle. As fluid accumulates, the sharp corner where the diaphragm meets the lateral chest wall fills in and the angle appears rounded or “blunted,” especially on an upright film. This sign can often be seen even with small effusions, as the fluid layers posteriorly. Lobar consolidation, by contrast, shows a dense opacity with air-filled bronchi (air bronchograms) and usually a different silhouette pattern. Hyperinflation implies increased lung volumes and flattened diaphragms, not a fluid collection. Mediastinal shift can occur with large effusions, but it is not the typical early sign and can be seen with other processes as well.

Fluid in the pleural space produces a recognizable change on chest X-ray, with the earliest and most specific clue being blunting of the costophrenic angle. As fluid accumulates, the sharp corner where the diaphragm meets the lateral chest wall fills in and the angle appears rounded or “blunted,” especially on an upright film. This sign can often be seen even with small effusions, as the fluid layers posteriorly.

Lobar consolidation, by contrast, shows a dense opacity with air-filled bronchi (air bronchograms) and usually a different silhouette pattern. Hyperinflation implies increased lung volumes and flattened diaphragms, not a fluid collection. Mediastinal shift can occur with large effusions, but it is not the typical early sign and can be seen with other processes as well.