Special Forces Medics Ability to Identify Wooden Foreign Bodies by Point-of-Care Ultrasound

Detection of retained foreign bodies (FB) is a difficult task in both austere environments and emergency departments, particularly when they are radiolucent and not detectable by plain radiographs. Failure to identify and remove them can lead to increased morbidity.

To determine the accuracy of Special Forces (SF) medics in detecting wooden FBs in tissue models, using point-of-care ultrasound.

A prospective, single-blinded, observational study using chicken thigh models was performed. Medics with no prior soft-tissue ultrasound experience received a 1-hour lecture on ultrasound, then scanned 10 tissue models for up to 3 minutes each. Participants were blinded to the models: five were free of FBs and five contained a single wooden FB of varying lengths (1, 2.5, 5, 7.5, or 10mm) at a depth of 5mm.

Twenty SF medics performed 200 total scans. For the detection of wooden FBs, sensitivity was 71.8% (95% CI 50.7-85.7) and specificity 82.0% (95% CI 61.1-92.6). The 10-mm FB was identified with 95% accuracy and had an overall sensitivity of 95% (95% CI 76.4-99).

SF medics with minimal ultrasound training are capable of accurately identifying soft-tissue wooden FBs with ultrasound. The FB size, orientation, and proximity to fibrous tissues were important factors in accurate identification. SF medics use of ultrasound to aid in the detection of superficial, soft-tissue FBs is an obtainable and valuable skill.