Radio-opacity of fishbones.

Bones are the largest group of foreign bodies found in the air and food passages. Fishbones which lodge in the tonsil can be easily seen and removed relatively easily. Those lodging in the pyriform fossa are well localized by the patient and can usually be seen on mirror examination. It would be useful to know which types of fishbones are radio-opaque and therefore likely to be shown by radiographs when mirror examination is difficult or fails to reveal a foreign body. Therefore a study was undertaken to ascertain the radio-opacity of the bones of ten different species of fish eaten in the British Isles.