Relative radio-opacity of commonly consumed fish species in South East Queensland on lateral neck x-ray: an ovine model.

OBJECTIVE

To determine the relative radio-opacity on plain x-ray of bones of fish species commonly consumed in South East Queensland.

DESIGN

A cadaveric sheep model was used to mimic the soft tissues of a human neck. Bones of 10 fish species were placed in the paratracheal tissues and adjacent to the larynx. X-rays were taken and the images (including four control images with no bones) were incorporated into a Microsoft PowerPoint presentation to be interpreted by emergency specialists and registrars. Observers were blinded to which specimens contained fishbones and which did not.

MAIN OUTCOME MEASURES

Sensitivity and specificity of plain x-rays for detecting impacted fishbones.

RESULTS

Significant interobserver variability was identified. Despite this, the overall specificity of plain x-rays was 90%. The sensitivity of the technique was 79% overall, but varied significantly between fish species.

CONCLUSION

Lateral soft tissue neck x-ray is an appropriate screening tool in cases of a suspected impacted fishbone. If a fishbone is identified on x-ray, the patient should be referred for endoscopy without further imaging. X-ray may be of limited value in cases of Dory or Spanish mackerel bone ingestion. In such cases, a computed tomography scan should be the first-line investigation.