Soft Tissue Foreign Bodies: ED Presentation, Evaluation, and Management

Authors: Christopher Creech, MD (EM Resident Physician, University of Kentucky), Julia Martin, MD, FACEP (Professor of Emergency Medicine, University of Kentucky) // Reviewed by: Alexander Y. Sheng, MD, MHPE (@TheShenger); Alex Koyfman, MD (@EMHighAK); Brit Long, MD (@long_brit)

Case:

A 38-year-old man presents with several days of worsening redness, pain, and swelling over his right forearm.  Four days ago, he was clearing brush from a corner of his yard. He sustained several what he thought were minor “cuts and scrapes” over his forearms. Most have healed but one area has become increasingly tender and red.  Vital signs are within normal limits. Exam reveals several superficial clean dry healing abrasions and one small puncture wound with surrounding erythema, edema, but without distinct fluctuance.

How should this patient be managed?

Background:

Soft tissue foreign bodies can present to the emergency department (ED) in the form of new wounds or as a complication of previous wounds. While it’s reported that only 7-15% of wounds actually contain a foreign body, almost all wounds have the potential to contain a foreign body [1,2].  Maintaining a high suspicion for foreign body as part of the initial evaluation can prevent complications and re-presentations.

Composition of foreign bodies can be broken down into three groups: metallic foreign bodies, organic foreign bodies such as wood, and inorganic foreign bodies such as plastic or glass [3].  Considering the composition of the suspected foreign body can guide both diagnosis and management.

Pearls:

-Maintain a high suspicion for foreign body in evaluation of all wounds.

-Composition of the suspected foreign body determines both diagnosis and management.

History and Physical Exam:

A thorough history should guide management of potential foreign bodies. Certain injury mechanisms, appearance and location of the wound, composition and shape of penetrating object are associated with higher likelihood of a retained foreign body. For instance, deep injuries such as puncture wounds in which depth cannot be directly visualized have a high association with foreign bodies. A perceived foreign body sensation more than doubles the likelihood that a foreign body is present [4]. Retained foreign body is suggested by the inability of a wound to heal, delayed infections, or infections resistant to antibiotic therapy [5].  The composition of the foreign body can help guide the appropriate imaging and whether removal of the foreign body is even necessary.

Wounds should be routinely explored as most foreign bodies are detectable during physical exam [2].  For open wounds, copious irrigation will aid in both visualization and removal of foreign bodies. Blind palpation with a gloved hand or blind grasping with instruments should be avoided due to risk of injury to surrounding structures and exposure to blood-borne diseases [6]. If suspicion for foreign body is high, extension of the wound margins with a scalpel if safe to do so may be necessary for a complete exam. Always consider neurovascular structures during initial exam as damage can occur from the foreign body itself or from attempts to remove the foreign body [4].

Pearls:

-Foreign body sensation, infection, and delayed healing all point toward possible foreign body.

-Routinely explore all wound presentations as most foreign bodies are detectable on exam.

Diagnosis:

If a foreign body is not visible during wound exploration, imaging studies will be necessary for diagnosis and localization.  Composition of the suspected foreign body can aid in the choice of initial imaging.

Plain radiography:

Metallic foreign bodies should easily be identified on plain films.  Gravel, sand, bone, teeth, pencil graphite, and some plastics are also visible on radiographs. Pieces of glass that are 2mm or larger are often visible on x-ray [7]. While radiography has been estimated to detect approximately 80% of foreign bodies in the ED, it cannot rule out a suspected radiolucent foreign body [8]. Multiple views are sometimes necessary to visualize the foreign body as bone or other surrounding structures can easily obscure it on a single view. Contrast and brightness of the image can be adjusted to match that of an underpenetrated film in order to better differentiate foreign body from surrounding tissue.

Ultrasound:

Sonography is a readily available tool for both identification and removal of soft tissue foreign bodies. It is particularly useful in the ED when the suspected foreign body is radiolucent such as wood. Pooled date has shown ultrasound to be 72% sensitive and 92% specific for detecting foreign bodies [1].

Soft tissue foreign bodies will present as a hyperechoic focus on ultrasound.  The majority of foreign bodies will also demonstrate an associated acoustic shadow, which is useful for differentiating a foreign body from hyperechoic anatomic structures such as scar tissue [8]. Edema, infection, and granulation tissue may be represented by a hypoechoic halo [9].

Sensitivity of detecting small foreign bodies has been shown to improve when using a high frequency linear transducer [8].  For evaluating hands or feet, a water bath using water or saline can improve patient comfort and visualization. Ultrasound visualization of shallow objects can be improved with a water bath by overcoming extreme “near field” limitations of the ultrasound [10].  Performing local hydrodissection around the foreign body with lidocaine or sterile saline can assist with both visualization and bedside removal [11].

Limitations of ultrasound are several. The ability to identify and remove foreign bodies using ultrasound is operator dependent. Acoustic shadowing from echogenic structures such as calcification, tendons, and bones can obscure foreign bodies. Certain body areas such as ears and web spaces have difficulty accommodating ultrasound probe and gel. The risk of false-positives is significant. And a negative bedside ultrasound does not exclude the presence of a retained foreign body if clinical suspicion is high. Advanced imaging may be necessary.

Computed Tomography (CT):

CT is better able to differentiate densities than plain radiography and thus is able to detect more types of foreign bodies [12]. Better density differentiation also allows for demonstration of wood, plastic, and organic materials not seen on plain radiographs as well as resulting inflammation and infection.  CT may be required for deeper foreign bodies, when there is concern for severe complications such as deep space infections, or involvement of a specific anatomic structure [3]. The obvious downsides to CT include cost, time, and radiation.

Magnetic Resonance Imaging (MRI):

MRI can be useful for detection of radiolucent foreign bodies.  Studies have shown MRI to be more accurate than other modalities for identifying plastic and organic matter such as wood or thorns.  It can be especially useful for showing surrounding structures such as nerves or blood vessels.  It should be avoided when evaluating potentially magnetic foreign bodies such as metal [5].

Pearls:

-Plain radiography is an efficient way to identify suspected radiopaque foreign bodies.

-Ultrasound is useful for radiolucent foreign bodies and can be used to aid in foreign body removal.

-Foreign bodies are hyperechoic on ultrasound with likely acoustic shadowing.

-Advanced imaging (CT, MRI) may be necessary to identify foreign bodies if clinical suspicion persists after negative x-ray and ultrasound, as well as to assess for related complications.

Management:

Once a foreign body is identified, the benefits of removal must be weighed against the risk of leaving it in place and iatrogenic injury from attempted removal in the ED.  Not all foreign bodies require removal, and not all removal needs to take place in the ED.  Composition of the foreign body is important. Asymptomatic, small, inert, deeply embedded foreign bodies can likely be left in place. Organic foreign bodies such as wood or thorns can lead to inflammation and infection and therefore need to be removed. Vegetation, chemically reactive material, or those with potential for allergic reaction or toxicity (eg. heavy metals) require removal.  Wounds that are heavily contaminated such as those with teeth or soil will require extensive irrigation and foreign body removal. Active infection or neurovascular compromise are indications for wound exploration and attempted removal of the foreign body. Foreign body sensation or ongoing pain are also reasonable indications for removal [3]. Foreign bodies close to fractured bone, impinging on nerves, vessels, tendons, joints, or vascular structures, also require removal.

If removal is attempted in the ED, the wound should be cleaned and prepped appropriately. Adequate lighting and wound exposure is crucial. Local anesthetic may be sufficient, but regional anesthesia should be considered for deeper wounds or more extensive exploration. There is no evidence that systemic antibiotics are required for clean wounds without infection, even in presence of a foreign body. Dirty wounds will likely benefit from antibiotics.  Additionally, ensure that tetanus vaccination is up to date [3].

A direct approach to exploration and removal through the existing wound can usually be employed upon initial evaluation [3]. In wounds such as puncture wounds where visualization is poor, the wound margins may need to be widened if safe to do so for appropriate visualization and foreign body removal [5].  Clean wounds in which the foreign bodies have been successfully removed can be closed with sutures. If the wound is infected or has retained foreign bodies, it should be allowed to heal by secondary intention [3].

An indirect approach may be necessary for chronic foreign bodies where the initial skin injury has healed over.  Ultrasound with appropriate sterile procedure can be very useful for determining the best approach for initial incision [3]. A larger elliptical incision may allow for easier wound exploration, and can still be easily closed after the procedure [6].

If reasonable attempts to locate the foreign body are unsuccessful, and there is active infection, injury, functional problems, or toxicity, surgical consultation is necessary for operative management.  If the foreign body is not actively causing harm, whether it failed attempts at removal or deliberately left in place, the patient will need to be informed of what to expect and plan for outpatient follow up.

Pearls:

-Not all foreign bodies require removal in the ED, and some don’t require removal at all.

-Dirty or infected wounds will likely require antibiotics and tetanus booster.

-Wound margins may need to be widened for direct removal.

-Chronic foreign bodies may require indirect incision.

-Ultrasound is a useful adjunct to aid in removal of foreign bodies not easily extracted using direct visualization.

Case Resolution:

Point of care ultrasound was used to evaluate the area of erythema and revealed a small opacity with acoustic shadowing. There was surrounding cobblestoning without a distinct fluid pocket.  The area was anesthetized with lidocaine and a 1cm incision was made over the suspected foreign body.  A 2mm thorn tip was removed from the wound by irrigation. The patient was started on a short course of oral antibiotics and was counseled on wound care and return precautions.

References / Further Reading:

1. Davis J, Czerniski B, Au A, Adhikari S, Farrell I, Fields JM. Diagnostic Accuracy of Ultrasonography in Retained Soft Tissue Foreign Bodies: A Systematic Review and Meta-analysis.Acad Emerg Med. 2015;22(7):777-787. doi:10.1111/acem.12714
2. Weinberger LN, Chen EH, Mills AM. Is screening radiography necessary to detect retained foreign bodies in adequately explored superficial glass-caused wounds?.Ann Emerg Med. 2008;51(5):666-667. doi:10.1016/j.annemergmed.2007.05.012
3. Skinner EJ, Morrison CA. Wound Foreign Body Removal. In:StatPearls. Treasure Island (FL): StatPearls Publishing; 2020.
4. Steele MT, Tran LV, Watson WA, Muelleman RL. Retained glass foreign bodies in wounds: predictive value of wound characteristics, patient perception, and wound exploration.Am J Emerg Med. 1998;16(7):627-630. doi:10.1016/s0735-6757(98)90161-9
5. Lammers RL. Soft tissue foreign bodies. In: Tintinalli JE, Strapczynski JS, Ma OJ, eds. Tintinalli’s Emergency Medicine. 8^th McGraw-Hill; 2016.
6. Halaas GW. Management of foreign bodies in the skin.Am Fam Physician. 2007;76(5):683-688.
7. Courter BJ. Radiographic screening for glass foreign bodies–what does a “negative” foreign body series really mean?.Ann Emerg Med. 1990;19(9):997-1000. doi:10.1016/s0196-0644(05)82562-4
8. Mohammadi A, Ghasemi-Rad M, Khodabakhsh M. Non-opaque soft tissue foreign body: sonographic findings.BMC Med Imaging. 2011;11:9. Published 2011 Apr 10. doi:10.1186/1471-2342-11-9
9. Little CM, Parker MG, Callowich MC, Sartori JC. The ultrasonic detection of soft tissue foreign bodies.Invest Radiol. 1986;21(3):275-277. doi:10.1097/00004424-198603000-00014
10. Blaivas M, Lyon M, Brannam L, Duggal S, Sierzenski P. Water bath evaluation technique for emergency ultrasound of painful superficial structures.Am J Emerg Med. 2004;22(7):589-593. doi:10.1016/j.ajem.2004.09.009
11. 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. doi:10.1002/jcu.22856
12. Jarraya M, Hayashi D, de Villiers RV, et al. Multimodality imaging of foreign bodies of the musculoskeletal system.AJR Am J Roentgenol. 2014;203(1):W92-W102. doi:10.2214/AJR.13.11743