A pneumothorax can be the consequence of instrumentation of the chest.
Thoracocentesis (pleural aspiration) was performed on this patient with a pleural effusion. After invasive procedures such as this, a chest X-ray should be requested, specifically to check for a pneumothorax. Further action, such as chest drain insertion, may be required.
This X-ray shows dense opacification of the right lower zone - due to consolidation and a residual effusion (arrows) - and a pneumothorax (asterisks).
The direct contact between air and water results in a flat interface (arrows) rather than the characteristic 'meniscus' shape of a simple pleural effusion.