<unk>  is defined as the presence of both air and fluid within the pleural space. An upright chest x-ray will show air fluid levels. The horizontal fluid level is usually well defined and extends across the whole length of hemithorax.
Hydropneumothorax
Hemothorax
Chylothorax
Urinothorax
Hemopneumothorax
Pneumothorax
Pulmonary hematoma
Pleural empyema