Handheld Metal Detector Localization of Ingested Metallic Foreign Bodies

Abstract

<h3>Objective</h3> To demonstrate the accuracy of handheld metal detectors (HHMDs) for identification and localization of ingested metallic foreign bodies when used by experienced and inexperienced investigators. <h3>Design</h3> Prospective study comparing HHMD scanning with radiography. <h3>Setting and Patients</h3> A consecutive sample of all eligible patients (N=176) presenting to the emergency departments of Children's Medical Center of Dallas, Dallas, Tex, and Children's Hospital of the King's Daughters, Norfolk, Va, who were known or suspected to have ingested a metallic foreign body. <h3>Intervention</h3> Each patient underwent HHMD scanning and radiographic evaluation. <h3>Main Outcome Measures</h3> Statistical evaluation compared HHMD scanning with radiography and experienced vs inexperienced investigator HHMD scanning to determine the accuracy of the screening tool and investigators. <h3>Results</h3> Experienced investigators performed HHMD scans on 140 subjects; inexperienced investigators scanned all subjects. Disease was defined as a foreign body in the esophagus on radiograph. The 3 experienced investigators demonstrated sensitivity of 100% (95% confidence interval [CI], 94%-100%), specificity of 92.4% (95% CI, 84.2%-97.2%), positive predictive value (PPV) of 90.9% (95% CI, 81.3%-96.6%), and negative predictive value (NPV) of 100% (95% CI, 95.1%-100%); the proportion correct was 95.7% (95% CI, 90.8%-98.4%). The inexperienced investigators demonstrated sensitivity of 95.7% (95% CI, 88.0%-99.1%), specificity of 81.0% (95% CI, 72.1%-88.0%), PPV of 77.0% (95% CI, 66.8%-85.4%), and NPV of 96.6% (95% CI, 90.4%-99.3%); the proportion correct was 86.9% (95% CI, 80.9%-91.5%). The McNemar test demonstrated no statistically significant difference between HHMD scanning by experienced vs inexperienced investigators. <h3>Conclusions</h3> Handheld metal detector scanning is an accurate, inexpensive, radiation-free screening tool and should be used for evaluation of patients suspected of ingesting coins and coinlike foreign bodies.