Causes of blunting of costophrenic angle

 The most common cause is pleural effusion, but blunting is not synonymous with effusion.

1. Pleural causes

Pleural effusion — most important/common

CHF

Parapneumonic effusion/empyema

Tuberculosis

Malignancy

Cirrhosis/hepatic hydrothorax

Nephrotic syndrome, etc.

Pleural thickening

Previous TB

Empyema

Hemothorax

Pleural malignancy

Asbestos-related disease

Pleural fibrosis/calcification

Post-pleural surgery

2. Extrapleural / pulmonary causes

Lower-lobe consolidation abutting the pleura

Atelectasis of the lower lobe

Peripheral lung mass

Pulmonary infarction

3. Technical/normal variants

Poor inspiration → apparent blunting of both CP angles

Supine film → pleural fluid may layer posteriorly rather than producing the classic meniscus

Obesity/chest wall soft tissue

Pleural recess not fully visualized

Causes of absent apical impulse

 Technical causes:

Obesity or thick chest wall

COPD- Emphysema, hyperinflated lungs

Impulse directly behind a rib

Pathological reasons:

Pericardial effusions 

Left pleural effusion

Dextrocardia- present on the right side