Written by Chris Thom
Spoon Feed
This case presentation and literature review highlights the important role of POCUS in foreign body diagnosis and removal.
Ultrasound can lead you to successful foreign body removal
Foreign bodies (FBs) frequently complicate soft tissue injuries. Their identification and removal are critical to avoid complications including infections, recurrent health care visits, and malpractice claims. Plain X-ray can fail to identify FBs that are organic or wood in composition. Foreign bodies are easily visualized on POCUS by their highly echogenic appearance, with high-frequency ultrasound transducers providing excellent resolution and ability to detect them. Wood FBs will cast a dark posterior acoustic shadow, while glass and metal often result in reverberation artifact. These features can be helpful in differentiating FBs from normal structures such as intermuscular fascia. FB removal can be facilitated with ultrasound via direct guidance of forceps to the object of interest.
How does this change my practice?
Ultrasound for FB identification is an easy skill to pick up. Prior studies demonstrate that physicians with minimal training have similar accuracy as radiologists and sonographers (1). A retained foreign body that might have otherwise been missed by X-ray is also very consequential and practice changing, as many of these benefit from removal at the time of identification. If any suspicion for a retained FB, search carefully through the area with your high-frequency transducer. Once identified, POCUS can also provide insight and guidance into successful removal strategies.
Pro Clips and Tips
When dealing with the fingers or hand, a water bath can make life much easier. You will not have to directly contact the probe with the skin surface and can reduce the discomfort of the exam and better visualize the tissue folds at the joint spaces. Removal of FBs can get much more complicated than simple identification, as FBs that are even a few millimeters deep can be difficult at times. Adequate anesthesia is critical and, at times, a well-selected US-guided peripheral nerve block can make life much easier. For example, the posterior tibial nerve block can make the entire plantar surface of the foot go numb, which is perhaps a better strategy than attempts at local injection into the plantar surface. Extending the wound slightly to accommodate a small pair of alligator forceps can be successful, and this can occur under active ultrasound guidance (2,3).
Source
Point-of-care ultrasound for foreign bodies. Emerg Med J. 2024 Dec 3:emermed-2024-214399. doi: 10.1136/emermed-2024-214399. Epub ahead of print. PMID: 39626896
Additional References
- Orlinsky M, Knittel P, Feit T, Chan L, Mandavia D. The comparative accuracy of radiolucent foreign body detection using ultrasonography. Am J Emerg Med. 2000;18(4):401-403.
- Paziana K, Fields JM, Rotte M, Au A, Ku B. Soft tissue foreign body removal technique using portable ultrasonography. Wilderness Environ Med. 2012;23(4):343-348.
- Rooks VJ, Shiels WE 3rd, Murakami JW. Soft tissue foreign bodies: A training manual for sonographic diagnosis and guided removal.J Clin Ultrasound. 2020;48(6):330-336.
