Handheld metal detector localization of ingested metallic foreign bodies: accurate in any hands?

OBJECTIVE 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. DESIGN Prospective study comparing HHMD scanning with radiography. SETTING AND PATIENTS 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. INTERVENTION Each patient underwent HHMD scanning and radiographic evaluation. MAIN OUTCOME MEASURES Statistical evaluation compared HHMD scanning with radiography and experienced vs inexperienced investigator HHMD scanning to determine the accuracy of the screening tool and investigators. RESULTS 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. CONCLUSIONS 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.