Validation of the use of electromagnetic fields for the location and collection of metal projectiles in necropsies.

Abstract

Objective: To validate the use of commercially available handheld metal detectors, routinely used in various settings, for the detection and recovery of projectiles and metallic fragments. The aim is to offer simple and cost-effective initial detection alternatives and to strengthen the process of locating and retrieving metallic elements in biological tissues, using a human cadaver model.

Introduction: Recovering evidence is a critical activity during medicolegal autopsies, especially in cases of violent deaths caused by firearm projectiles. In such cases, projectiles and/or metallic fragments may migrate through body cavities or remain lodged in hollow viscera, large vessels, clothing, packaging, among other locations, making their recovery challenging.

Methodology: A handheld metal detector was used to locate projectiles and metallic objects on a corpse, its packaging, and clothing. Sensitivity, specificity, and overall and specific positive and negative predictive values ​​were calculated for each anatomical location.

Results: An overall sensitivity of 83.33% and specificity of 100% were obtained. Positive predictive value = 1; false positive rate = 0.00; negative predictive value = 0.60; false negative rate = 0.17. For smaller objects, equal to or less than 5 mm in diameter specificity = 100%, sensitivity = 62.5% in certain anatomical regions.

Conclusion: These devices were found to be useful tools for detecting metallic projectiles during autopsies, particularly for objects measuring 7 mm or more, in rural or open areas where access to X-ray equipment is limited. For smaller objects, equal to or less than 5 mm in diameter, although specificity remains at 100%, the sensitivity of 62.5% in certain anatomical regions suggests that further research is needed to improve detection capabilities for these items in cadavers.