A 'complete white out' of the hemithorax describes total opacification of one side of the thoracic cavity.

The main causes are:

- massive pleural effusion

- pneumonectomy

- total collapse

- total lung consolidation

The tracheal position is key to the likely cause - in the case it has been pushed to the contralateral side.

This is due to the mass effect from a pleural effusion.