The utility of plain radiography in assessment of upper aerodigestive tract fishbone impaction: an evaluation of 22 New Zealand fish species.

Aims: To determine the utility of plain radiography for suspected upper aerodigestive tract fishbone impaction in New Zealand fish species.

Methods: Tissue densities of the least and most dense regions of the upper aerodigestive tract were measured on a lateral soft tissue X-ray of the neck. Densities of the measured regions were reproduced in two custom manufactured radiological phantoms. Epipleural bones from 22 commonly eaten New Zealand fish species were X-rayed within these phantoms. Forty-one Emergency Department doctors graded the X-ray visibility of each bone using a five point visual analogue scale.

Results: Twenty species (90.9%) returned a sensitivity of 95% or greater when viewed within the least dense phantom. The two species with lesser sensitivities within the least dense phantom were Red Cod (90.2%) and Ray's Bream (58.8%). Only one species (Black Cardinalfish; 4.5%) returned a sensitivity of 95% or greater when viewed within the most dense phantom.

Conclusions: Bones from the majority of commonly eaten New Zealand fish species are poorly visible when X-rayed in a background of soft tissue density. Given fishbones frequently impact in regions of high tissue density, plain radiography would appear insufficiently sensitive to exclude upper aerodigestive tract fishbone impaction.