This is an emergency that most people are familiar with, even if it’s only from cartoons and TV shows: the swallowed key, coin, or other item. Whether swallowed or inhaled, when the item is made from a solid material, such as certain plastics or metal, it will show up very clearly with a simple chest x-ray. These materials are denser than bone and soft tissues, so x-rays do not pass through them; this means that they show up as white, or ‘radiopaque’ on the x-ray image.

This child has swallowed a nail, which can be seen quite clearly at the bottom of the x-ray image.

Swallowed item (‘foreign body’)