Page 95 - JSOM Winter 2024

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

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Kyler C. Osborne, MD *; Theodore J. McLean, MD ;
Jason D. Heiner, MD ; Vincent L. Ball, MD 4
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ABSTRACT
Background: Detection of retained foreign bodies (FB) is a as viable imaging options with increased sensitivity for FB
difficult task in both austere environments and emergency detection when compared with plain radiographs. MRI,
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departments, particularly when they are radiolucent and not however, is often unavailable, relatively expensive, and more
detectable by plain radiographs. Failure to identify and remove time- consuming. Meanwhile, CT is also a less desirable option
them can lead to increased morbidity. Objective: To determine given its increased cost and the risks associated with exposure
the accuracy of Special Forces (SF) medics in detecting wooden to ionizing radiation. Ultrasound is an ideal imaging modality
FBs in tissue models, using point-of-care ultrasound. Meth- given its ease of use by inexperienced operators, lack of ioniz-
ods: A prospective, single-blinded, observational study using ing radiation, overall portability, and improved sensitivity over
chicken thigh models was performed. Medics with no prior plain radiographs in the detection of radiolucent materials. 10
soft-tissue ultrasound experience received a 1-hour lecture on
ultrasound, then scanned 10 tissue models for up to 3 minutes Point-of-care ultrasound (POCUS) has been pushed further
each. Participants were blinded to the models: five were free of forward to austere environments and on the battlefield. Spe-
FBs and five contained a single wooden FB of varying lengths cial Operations medics, military physicians, and other austere
(1, 2.5, 5, 7.5, or 10mm) at a depth of 5mm. Results: Twenty or resource-limited providers frequently employ POCUS to
SF medics performed 200 total scans. For the detection of aid in rapid evaluation of traumatic and other immediately
wooden FBs, sensitivity was 71.8% (95% CI 50.7–85.7) and life-threatening injuries. However, there is minimal focus
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specificity 82.0% (95% CI 61.1–92.6). The 10-mm FB was on soft-tissue sonography and FB detection. Case reports and
identified with 95% accuracy and had an overall sensitivity small investigations have reported varying provider ability to
of 95% (95% CI 76.4–99). Conclusions: SF medics with min- detect wooden FBs. 12,13
imal ultrasound training are capable of accurately identifying
soft-tissue wooden FBs with ultrasound. The FB size, orienta- Military servicemembers are regularly at risk for retained
tion, and proximity to fibrous tissues were important factors soft-tissue FBs from bullet fragments, shrapnel, improvised
in accurate identification. SF medics use of ultrasound to aid explosive devices (IEDs), explosions of wooden structures,
in the detection of superficial, soft-tissue FBs is an obtainable or densely vegetated areas in austere combat environments.
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and valuable skill. Wooden FBs are especially irritating to tissues and may cause
a reactive inflammatory reaction and persistent pain. 14,15 They
Keywords: wooden foreign bodies; ultrasound; military medics; may precipitate infections, cellulitis, abscesses, soft tissue in-
special forces; special operations; POCUS fections, septic arthritis, or osteomyelitis. Therefore, prompt
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identification and removal is crucial. If a wooden FB is sus-
pected, additional imaging modalities such as ultrasound must
be used for evaluation. 16–18
Introduction
Detection of superficial retained foreign bodies (FBs) is a Prior studies have examined the sensitivity and specificity of ul-
difficult task in austere environments as well as in the emer- trasound in detecting a variety of radiolucent materials. 1,5,7,19–21
gency department (ED), particularly when the FBs are radio- Wood, glass, plastic, gravel, metal, and rubber FBs have all
lucent and not easily detected by plain radiographs or when been previously examined, and these studies routinely involve
radiographs are not available. History and physical exam emergency physicians, resident physicians, sonographer techni-
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are often not enough to confirm or rule out the presence of cians, and radiologists. The tissues examined have varied as
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an FB. Failure to identify and remove these FBs can result well, with some studies using human cadavers and others food-
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in significant morbidity and potentially mortality. Histori- grade chicken thighs, which sonographically replicate human
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cally, plain radiographs have been used to identify FBs in tis- tissue with a high degree of fidelity. 1,12,13,20 Previous investiga-
sue, though their sensitivity in the identification of radiolucent tions show variations in detection by emergency physicians,
substances (e.g., wood, glass, rubber) is poor, and the false with reported sensitivity ranging from 50% to 96.7%. 1,20 Lack
negative rate is unacceptably high. As such, other modalities, of standardized FB size in these previous investigations make it
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such as MRI, ultrasonography, and CT, have been explored challenging to infer the detection abilities of medical providers.
*Correspondence to kyler.c.osborne.mil@health.mil
1 CPT Kyler C. Osborne is a Resident Physician affiliated with the Department of Emergency Medicine, Madigan Army Medical Center, Joint Base
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Lewis-McChord, WA. CPT Theodore “Jamie” McLean is a Resident Physician affiliated with the Department of Emergency Medicine, Madigan
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Army Medical Center, Joint Base Lewis-McChord, WA. Jason D. Heiner is an Attending Physician with the Department of Emergency Medicine,
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University of Washington, Seattle, WA. LTC (R) Vincent L. Ball is an Attending Physician with the Department of Emergency Medicine, Madigan
Army Medical Center, Joint Base Lewis-McChord, WA.
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