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CHAPTER 45: Soft Tissue Foreign Bodies 307  PROPHYLACTIC ANTIBIOTICS Although infection occurs in 3% to 8% of lower extremity lacera tions, there is no evidence to support routine antibiotic prophylaxis in uncomplicated lacerations (see Chapter 47, “Postrepair Wound Care”). However, use prophylactic antibiotics for complicated lacerations in the setting of bites, open fractures, tendon or joint involvement, presence of foreign debris, and obvious infections. Diabetes and other predisposing medical conditions, wound contamination, and laceration length >5 cm are factors that predispose to wound infection. Most lower extremity wound infections are due to either methicillinsensitive Staphylococcus and/or Streptococcus species. Animal bites to the leg and foot require additional coverage for Pasteurella. Asplenic or immunocompromised patients who sustain a dog bite should receive coverage against Capnocytophaga canimorsus. Amoxicillin-clavulanate will cover all four organisms (see Chapter 46, “Puncture Wounds and Bites”). Staphylococcus and Streptococcus are the most common cause of soft tissue infections following plantar puncture wounds. Pseudomonas aeruginosa is a frequent cause of osteomyelitis and osteochondritis when the puncture occurs through the sole of a shoe (see Chapter 46). Open fractures associated with wounds <10 cm in size with out extensive soft tissue damage or contamination should receive antibiotic prophylaxis using cefazolin, 2 grams IV (alternatively clindamycin, 900 milligrams IV , if severe beta-lactam allergy), plus vancomycin, 15 milligrams/kg IV if there is known methicillinresistant Staphylococcus aureus colonization. 41 For open fractures with extensive soft tissue damage, antibiotic prophylaxis should use ceftriaxone, 2 grams IV , with metronidazole, 500 milligrams IV , added if soil or fecal contamination is present and vancomycin, 15 milligrams/kg IV , if there is known methicillin-resistant S. aureus colonization. REFERENCES The complete reference list is available online at www.TintinalliEM.com. Soft Tissue Foreign Bodies Richard Lammers Joshua Mastenbrook INTRODUCTION Soft tissue foreign bodies may be encountered when managing new wounds or evaluating complications of old wounds. This chapter dis cusses methods of detecting and removing them. In the setting of a fresh wound, methodically search fresh wounds for contamination by foreign material. If a foreign body is discovered within a wound cavity or deeply embedded in tissue, decide if removal of the material is urgent, can be delayed, or is even necessary. The deci sion to remove foreign bodies located below the dermal layer of skin depends on the size, location, composition, accessibility, and anticipated mechanical and inflammatory effects of the object. Many foreign bodies should be removed in the ED; for example, all foreign material within the cavities of fresh lacerations should be irrigated away, debrided, or extracted with instruments. Occasionally, patients with subcutaneous foreign bodies should be referred to appropriate specialists for delayed removal. Most foreign bodies are detectable during clinical examination. 1,2 Imaging studies are used to evaluate wounds when a concealed object is possibly present. CHAPTER PATHOPHYSIOLOGY Transient inflammation is an integral part of normal wound healing. A small amount of foreign debris in a wound provokes an inflamma tory response in an effort to eliminate or contain the invader.

ation. 1,2 Imaging studies are used to evaluate wounds when a concealed object is possibly present. CHAPTER PATHOPHYSIOLOGY Transient inflammation is an integral part of normal wound healing. A small amount of foreign debris in a wound provokes an inflamma tory response in an effort to eliminate or contain the invader. Large quantities of devitalized tissue, foreign debris, bacteria, or other irritants present within a wound intensify this protective response. Excessive or prolonged inflammation delays wound healing and destroys surrounding soft tissue and bone, producing periosteal reactions, osteolytic lesions, synovitis, and arthritis. If the body fails to dissolve or extrude foreign material, it may become encapsulated within a fibrous capsule. Once a retained foreign body is encapsu lated, inflammation subsides. The type, timing, and intensity of an inflammatory reaction are determined primarily by the chemical composition and physical form of the foreign object. Material that is inert—such as glass, metal, or plastic— may not elicit any abnormal tissue response. Objects with smooth, nonporous surfaces produce less inflammation and fibrosis than those with rough surfaces. Most metals are inert, but those that oxidize will cause mild to moderate inflammation. Earrings with studs dipped in gold paint cause earlobe swelling and inflammation when the paint flakes off. Vegetative foreign bodies, such as wood, thorns, and spines, trigger the most severe inflammatory reactions. Sea urchin spines, other marine foreign bodies, and hair may cause chronic inflammation with granuloma formation. In some cases, inflammation is caused by a local toxic reaction. For example, blackthorns contain an alkaloid that produces intense inflam mation. The oils and resins in redwood and cedar splinters also cause considerable inflammation. Sea urchin spines and catfish spines con tain venom that causes severe burning pain at the puncture site and a variety of systemic symptoms (see Chapter 213, “Marine Trauma and Envenomation”). A sudden, local inflammatory reaction from a rose thorn or cactus spine may be an allergic response to fungi on the plant. Some cacti cause a delayed hypersensitivity reaction. Systemic toxic and allergic reactions are unusual but serious complications of foreign bodies. Although toxicity is unlikely, foreign bodies containing lead, such as bullets, have the potential to produce systemic lead poisoning, particularly if they are in contact with pleural, peritoneal, cerebrospinal, or joint fluid. 4-6 Infections are the most common complication of retained foreign bodies, producing local wound infection, cellulitis, abscess formation, lymphangitis, tenosynovitis, bursitis, septic arthritis, and osteomyelitis. 7,8 Infections associated with retained soft tissue foreign bodies are characteristically resistant to pharmacologic therapy; antibiotics, antiinflammatory drugs, and steroids may produce a partial regression but seldom eradicate the infection. 9 Some infections will resolve spontane ously once the foreign bodies are removed. Bacteria are infrequently detected after plant thorn injuries, possibly due to the empiric use of antibiotics, but when bacteria are found, gram-negative aerobic bacillus Enterobacteriaceae family member Pantoea agglomerans is a commonly reported isolate. 10,11 Vegetative foreign bodies may also cause fungal infections, particularly in immunosuppressed patients. Foreign objects can also cause mechanical damage by compressing or lacerating anatomic structures or occluding vessels. Repeated movement of tissue containing a foreign object increases the fibrous reaction.

te. 10,11 Vegetative foreign bodies may also cause fungal infections, particularly in immunosuppressed patients. Foreign objects can also cause mechanical damage by compressing or lacerating anatomic structures or occluding vessels. Repeated movement of tissue containing a foreign object increases the fibrous reaction. CLINICAL FEATURES  HISTORY Every wound has the potential for concealing a foreign body, but only a small percentage of lacerations and puncture wounds actually contain them. 1,2,12 Historical factors associated with a higher risk for a retained foreign body include the mechanism of injury, composition and shape of the wounding object, and the shape and location of the resulting wound. Blows to the mouth may fracture teeth, embedding fragments in the lip, tongue, or buccal mucosa of the patient or in the hand of the assailant. 13-15 Objects that shatter, splinter, or break in the process of causing a wound often leave remnants behind. Thorns, spines, and sharp wooden branches are usually brittle and tend to penetrate deeply Tintinalli_Sec06_p0267-0328.indd 307 8/2/19 7:16 PM

e, or buccal mucosa of the patient or in the hand of the assailant. 13-15 Objects that shatter, splinter, or break in the process of causing a wound often leave remnants behind. Thorns, spines, and sharp wooden branches are usually brittle and tend to penetrate deeply Tintinalli_Sec06_p0267-0328.indd 307 8/2/19 7:16 PM 308 SECTION 6: Wound Management FIGURE 45-1. A. A diabetic patient presented with redness, swelling, and mild pain of her left foot. Although she admitted to walking barefoot on occasion, she had no recollection of stepping on a sharp object. B. A small, healing puncture wound was visible on the plantar surface of her foot. C. Lateral radiographic view. into puncture wounds before breaking. Wood splinters are notorious for fragmenting, especially when they are pulled out of a puncture wound. Patients impaled by long, thin metallic objects, such as hypodermic or sewing needles, may remove them without realizing that a portion of the object broke off beneath the skin surface. Both remnants of a needle and impurities in street drugs can cause persistent pain or abscess formation at the site of IV drug use. Nails that penetrate socks and shoes may drive leather, rubber, or cloth into the plantar surface of a patient’s foot. Blunt objects with a diameter >4.5 mm may push a plug of skin deep into a wound, resulting in an epidermal inclusion cyst. If any object pulled from a wound does not appear intact, the wound should be explored for further contaminants. The patient’s description of a foreign body sensation in a fresh wound is a useful sign in adults—the perception of a foreign body more than doubles the likelihood of one being present. 12 However, foreign body sensation is less useful in verbal-age children. 16 If a patient reports a sudden, sharp pain on the bottom of the foot while walking barefoot, consider the possibility of impalement with a needle, toothpick, splinter, or shard of glass. Patients with retained foreign bodies may present to the ED after a wound heals complaining of sharp pain with movement or with pres sure over the site. Failure of a wound to heal also may be evidence of a retained irritant. Chronic, delayed, and recurrent infections are associ ated with retained foreign bodies (Figure 45-1). New puncture wounds that become infected and infections that are resistant to antibiotic therapy suggest a retained foreign body. Arthritis in a joint near an old puncture wound may be plant thorn–induced synovitis. 8,9 Unsuspected foreign bodies may present as soft tissue masses.17  PHYSICAL EXAMINATION Physicians are occasionally surprised by foreign bodies that are embed ded in small or seemingly superficial wounds. Physical findings that are associated with the presence of a foreign body include a discoloration or visible mass under the epidermis, palpation of a mass, sharp welllocalized pain with palpation over or adjacent to a wound, and limitation of passive range of movement of a joint near a wound. Old wounds with retained foreign bodies may have a persistent purulent drainage, a chronic draining sinus, or a chronic granulomatous reaction. A sterile abscess that complicates wound healing may be the result of a foreign body. Some foreign bodies are discovered in wounds unexpectedly, but most are found during a deliberate and careful exploration of wounds considered to be at risk. 1,2,12 Adequate lighting, good hemostasis, appropriate anesthesia, and patient cooperation are essential. Magnifying loupes can enhance visualization of small debris fragments or foreign bodies. Make effort to visually inspect all recesses of a wound. Wounds deeper than 5 mm and wounds whose depth cannot be visualized have a higher association with foreign bodies.

ropriate anesthesia, and patient cooperation are essential. Magnifying loupes can enhance visualization of small debris fragments or foreign bodies. Make effort to visually inspect all recesses of a wound. Wounds deeper than 5 mm and wounds whose depth cannot be visualized have a higher association with foreign bodies. If punctures and other narrow wounds make direct visualization difficult and there is concern about a foreign body below the surface, the wound margins should be extended with a scalpel (Figure 45-2). Tintinalli_Sec06_p0267-0328.indd 308 8/2/19 7:16 PM

ropriate anesthesia, and patient cooperation are essential. Magnifying loupes can enhance visualization of small debris fragments or foreign bodies. Make effort to visually inspect all recesses of a wound. Wounds deeper than 5 mm and wounds whose depth cannot be visualized have a higher association with foreign bodies. If punctures and other narrow wounds make direct visualization difficult and there is concern about a foreign body below the surface, the wound margins should be extended with a scalpel (Figure 45-2). Tintinalli_Sec06_p0267-0328.indd 308 8/2/19 7:16 PM CHAPTER 45: Soft Tissue Foreign Bodies 309 AB C FIGURE 45-2. This patient’s leg was punctured by a wooden stake 2 days before presentation. A. Surrounding cellulitis and point tenderness lateral to the wound indicated the probability of a retained foreign body. B. The entrance to the wound was extended. C. A 1.7-cm piece of wood was removed. TABLE 45-1 Imaging Modalities for Detection of Soft Tissue Foreign Bodies 20-23 Material Plain Radiographs US CT MRI Wood Poor Good Moderate to good Moderate Metal Excellent Good Excellent Poor Glass Excellent Good Excellent Good Organic (most plant thorns and cactus spines) Poor Good Good Good Plastic Moderate Moderate to good Good Good Palm thorn Poor Moderate Good Good Wounds that penetrate deeply into adipose tissue are difficult to explore and easily hide foreign material. Gentle probing with a hemostat is a less effective but sometimes acceptable alternative to wound exploration when the wound is narrow and deep and extending the wound is not desirable. This method is used frequently to evaluate plantar punc ture wounds caused by nails and to search for clear glass, which is diffi cult to see in a wound. A closed hemostat should be introduced into the wound and either used as a probe or spread open and then withdrawn. If an instrument strikes a metallic or glass foreign body, it will produce a grating sensation. The instrument should not be used to grasp blindly in hopes of clamping an unseen object. Blind probing is especially dan gerous in hands, feet, or face, where direct visualization is the preferred method of exploration. DIAGNOSIS Imaging studies should be ordered in most cases in which a retained foreign body is suspected but not found during wound exploration or when exploration of the entire wound is technically impossible. 3,18 Imaging is also useful after initial removal of multiple foreign bodies to determine if all the pieces were found. Four imaging modalities are available: plain radiography, US, CT, and MRI. 19 The sensitivity and specificity of each imaging modality depend on the object’s size, shape, density, and orientation relative to the imaging beam (Table 45-1). 3,19 Materials that are the same density as surrounding soft tissue are difficult to see with any type of radiographic or sonographic technique.  LOCALIZATION METHODS Accurate localization of a foreign body before removal is important because blind searching is time consuming and can cause further injury. However, it is usually easier to detect the presence of a foreign body than to locate its exact position. If a foreign body is radiopaque, one can estimate its location and depth by taping radiopaque skin markers, such as lead circles, paper clips, or a grid, on the skin at the wound entrance or directly over the object. 24 With multiple projections, the object can be seen in relation to the markers. Hypodermic needles can be used as skin markers. Two or three needles are inserted into the skin near the object at approximately 90 degrees to each other to provide a frame of reference around the object. Plain films taken in multiple projections allow the physician to gauge the distance of the object from the closest needle or its distance between two needles (Figures 45-3 and 45-4). The limitations of this technique are that it does not provide a true three-dimensional view and that images on radiographs are distorted by divergence and parallax.

e projections allow the physician to gauge the distance of the object from the closest needle or its distance between two needles (Figures 45-3 and 45-4). The limitations of this technique are that it does not provide a true three-dimensional view and that images on radiographs are distorted by divergence and parallax. Tendons and other structures may block the most direct path to the foreign body.  IMAGE STUDY SELECTION Unless a foreign body is embedded at a relatively superficial level or lies within the cavity of a fresh wound, it will not be easily detected or located by physical examination. If a foreign body is suspected based on the mechanism of injury but not found during exploration of a wound, a radiograph should be ordered first, because plain radiography will detect as many as 80% to 90% of all foreign bodies. It is also prudent to order films if a patient believes there is a retained object. 12,16,18 If the wound was caused by metal, glass, or gravel and no foreign body was found on plain films or wound exploration, the physician can end the search. For objects not routinely visible (or not found) on plain radiog raphy, like wood, sonography is the modality of choice, with CT or MRI as alternatives. 19 In summary, no single imaging modality is ideal for all types of foreign bodies.  PLAIN RADIOGRAPHY Most foreign bodies that can be missed during the initial clinical evaluation can be seen on plain radiographs, but the images must be inspected Tintinalli_Sec06_p0267-0328.indd 309 8/2/19 7:16 PM

RI as alternatives. 19 In summary, no single imaging modality is ideal for all types of foreign bodies.  PLAIN RADIOGRAPHY Most foreign bodies that can be missed during the initial clinical evaluation can be seen on plain radiographs, but the images must be inspected Tintinalli_Sec06_p0267-0328.indd 309 8/2/19 7:16 PM 310 SECTION 6: Wound Management FIGURE 45-4. Needle markers are used to triangulate the location of a radiopaque foreign body. A. Plain radiograph, anteroposterior view. B. Oblique view. carefully to detect small and faint objects. 3 Metal, mammalian bone, some types of fish bones (cod, haddock, grey mullet, red snapper, and sole), teeth, pencil graphite, certain plastics, glass, gravel, sand, and aluminum are visible on plain radiographs. Almost all glass is visible on radiographs if it is 2 mm or larger, and glass does not have to contain lead to be visible on plain films ( Figure 45-5). 25 A radiopaque fragment is more easily seen if its long axis is positioned parallel to the central ray of the x-ray beam, increasing its apparent density; thus, a foreign body may be evident on one radiographic view but not another. Obtain plain film radiographs using an underpenetrated soft tissue technique, producing a lighter image that increases the contrast between the foreign body and surrounding tissue. If the radiograph is displayed on a digital imaging system, the contrast and brightness of the image can be adjusted to achieve the same effect as an underpenetrated film. Digital edge enhancement adjustments may make the foreign object stand out from the background. Radiographs should be taken in multiple projections to separate the shadow of the foreign body from underlying bone and to help gauge the depth of the object in the tissue (Figure 45-6). Chronic inflammatory changes may create secondary bony changes, such as osteolytic and osteoblastic lesions, pseudotumor formation, and periosteal reaction, revealing the object’s location. Many common or highly reactive materials, such as wood, thorns, cactus spines, some fish bones, other organic matter, and most plastics, are not visible on plain radiographs. 3,19,26 Sometimes, there is indirect evidence of their presence. A radiolucent filling defect may occur when the object is less dense than surrounding tissue. However, even radiopaque foreign bodies may be invisible on plain films if they are obscured by, or impacted in, bone.  COMPUTED TOMOGRAPHY CT is capable of detecting more types of foreign materials than plain film radiography because it is 100 times more sensitive in differentiating densities (Figure 45-7). 19 One study found CT to be superior to plain radiography for detecting glass foreign bodies <3 mm in size. 27 Subtle density differences can be distinguished with a narrow radiographic density window adjustment, particularly if a computer workstation is used to vary the gain and contrast settings. Thorns, spines, wood splinters and toothpicks, fish bones, and plastic foreign bodies can be identified with CT. 3 In dry wood, the interstices between the fibers are filled with air, imparting reduced radiodensity and making dry wood less visible on CT.19 Water-rich wood, either fresh from a tree or as occurs when dry wood has FIGURE 45-3. Hypodermic needles used as skin markers. Tintinalli_Sec06_p0267-0328.indd 310 8/2/19 7:16 PM

In dry wood, the interstices between the fibers are filled with air, imparting reduced radiodensity and making dry wood less visible on CT.19 Water-rich wood, either fresh from a tree or as occurs when dry wood has FIGURE 45-3. Hypodermic needles used as skin markers. Tintinalli_Sec06_p0267-0328.indd 310 8/2/19 7:16 PM CHAPTER 45: Soft Tissue Foreign Bodies 311 FIGURE 45-5. A. The marker points to a glass fragment in the plantar surface of this patient’s foot on the lateral view of this radiograph. B. Oblique view. FIGURE 45-6. A. The identity of this metallic foreign body is not apparent on the anteroposterior view of this radiograph. B. The shape and depth of the blade are best seen on the lateral view. C. Oblique view. been embedded in tissue long enough to absorb serohematic fluid, is more visible as a slightly hyperdense object on CT.28 CT will often detect the inflammatory response to an object that has been in place long enough to elicit the reaction. CT may detect objects embedded in bone, and isodense objects may be outlined by surrounding air within the wound. Digital edge enhancement can fur ther improve the visibility of these objects. CT images can be created in multiple planes and can demonstrate the relationship of a foreign object to important anatomic structures. The principal disadvantages of CT are its cost, higher radiation dose, and the fact that wood and other organic material have radiographic density close to water, making them difficult to distinguish from surrounding tissue. Another pitfall of CT is that wood foreign bodies may initially mimic air bubbles on CT images.  ULTRASOUND US is becoming the modality of choice for identifying radiolucent foreign bodies, as well as for directing exploration and foreign body removal. 30-35 US can identify a wide variety of soft tissue foreign bodies such as wood, fish bones, sea urchin spines, other organic material, fiber, and plastic, with ≥94% sensitivity for foreign bodies >4 to 5 mm (Figure 45-8). 36-41 However, the sensitivity and specificity of this test are highly dependent on the size and sonographic nature of the foreign body, 42,43 as well as the number of foreign bodies, the presence of confounding factors (e.g., bone, blood, purulence, scars, old sutures) associated with the foreign body, and operator skill and experience. Foreign bodies appear as hyperechoic foci, usually with acoustic shadowing extending distally. 44 Metal is brightly echogenic and has an associated reverberation artifact (comet tail), while glass has a more scattered reverberation artifact. Wood, plastic, gravel, and sand are hyperechoic and produce an acoustic shadow. 33 A hyperechoic rim, or halo sign, indicates an abscess or granuloma around the object. Sonography can estimate the depth of a foreign body below the skin surface. With experience, sonography can be applied to body areas previously difficult to image for soft tissue foreign bodies, such as the hands and feet. 45-48 Soft tissue gas may not reduce the ability to detect a foreign body but does decrease the ability to discriminate between metal and wood. 49 An important technical aspect of US for soft tissue foreign body detection is the transducer frequency. 50 Higher frequencies have a reduced effective depth of penetration for the US wave. A 3.5-MHz Tintinalli_Sec06_p0267-0328.indd 311 8/2/19 7:16 PM

does decrease the ability to discriminate between metal and wood. 49 An important technical aspect of US for soft tissue foreign body detection is the transducer frequency. 50 Higher frequencies have a reduced effective depth of penetration for the US wave. A 3.5-MHz Tintinalli_Sec06_p0267-0328.indd 311 8/2/19 7:16 PM 312 SECTION 6: Wound Management FIGURE 45-8. A. Tooth fragments can be embedded in facial and hand wounds. Sonographic image of an intact tooth. B. Fragments of shoes can be found in plantar puncture wounds. Sonographic image of rubber from sole of a shoe. Object is slightly hyperechoic; note the flat edge and acoustic shadowing. C. Fragments of clothing can be carried into gunshot wounds. Sonographic image of cloth (cotton). D. Sonographic image of a small fragment of glass; note the acoustic shadow. E. Sonographic image (long axis parallel to the scan plane) of a metal sewing needle; note the reverberation artifact typical of metallic objects. F. Sonographic image (short axis) of a sewing needle with a comet tail artifact. G. Sonographic image (long axis) of a wooden toothpick that was invisible on plain film radiography. H. Sonographic image (short axis) of a wooden toothpick surrounded by air that was invisible on plain film radiography. I. Sonographic image (long axis) of a cactus spine that was invisible on plain film radiography. J. Sonographic image (short axis) of a cactus spine that was invisible on plain film radiography; note the acoustic shadow. FIGURE 45-7. This patient sustained forehead lacerations when he struck his head on a car windshield. Glass foreign bodies were not identified before wound closure and were not visible on plain films, but were evident on CT. foreign bodies within their acoustic shadows, so these areas must be scanned slowly to detect foreign bodies that are small or oriented per pendicular to the skin surface. Some areas of the body that are prone to foreign body penetration, such as the web spaces of the hands or toes, may not accommodate a US probe using standard gel. In this circumstance, a water-bath interface between the probe and body part is useful. 45-47,50,51 False-positive findings result in an unnecessary surgical dissection. Falsepositive rates for sonography vary from 3% to 46% in clinical case series, depending on the material being studied. 39,41-43,52,53 Accuracy of detection will increase with physician experience. However, a negative bedside US does not exclude the possibility of a retained foreign body when a history and physical exam are concerning for a retained foreign body. In such cases, further radiologic imaging or delayed assessment may be necessary. Once a foreign body is confirmed by plain films or CT studies, US can be used in place of fluoroscopy to guide an instrument to the object during retrieval.30-32,45,46 The scanning beam should be oriented parallel to the long axis of a hemostat, which can be directed toward the long axis of the foreign body. Transverse and longitudinal scans provide views in multiple planes. A 7.5-MHz linear-array transducer can be used to find objects that are small and superficial (up to 5 cm deep), and a 5.0-MHz transducer can be used for larger and deeper objects. The linear scan is preferred for localization, and the sector scan for retrieval. 30 The primary advantage of sonography is the avoidance of radiation exposure. US may also be useful to localize and then confirm successful foreign body removal, for objects that were initially identified using other imaging modalities.

The linear scan is preferred for localization, and the sector scan for retrieval. 30 The primary advantage of sonography is the avoidance of radiation exposure. US may also be useful to localize and then confirm successful foreign body removal, for objects that were initially identified using other imaging modalities.  MAGNETIC RESONANCE IMAGING MRI can detect nonmetallic radiolucent foreign bodies and, in com parison studies, is more accurate (less sensitive than US but fewer falsepositive interpretations) than any other modality in identifying wood, plastic, spines, and thorns. 3,19,54 MRI should not be used with gravel or metal-containing foreign bodies because ferromagnetic streaks obscure visualization. MRI may provide more information than CT about the position of a foreign body relative to (and its effects on) nearby structures, such as tendons, neurovascular bundles, joints, and muscles.  FLUOROSCOPY Bedside fluoroscopy accurately detects radiopaque (metal, gravel, glass, and pencil graphite) foreign bodies as small as 3 mm. 55,56 Using fluoroscopy to accurately detect glass foreign bodies can be accomplished in transducer will locate foreign bodies that are as deep as 10 cm, a 5-MHz transducer at depths of approximately 7 cm, a 7.5-MHz transducer at depths of 5 cm, and a 12.5-MHz transducer at depths of 2.0 to 0.2 cm. Conversely, the resolution of the image—ability to distinguish two adjacent objects and detect small objects—is greatest with higher frequencies. Thus, low frequencies can detect larger objects at greater depth but may miss smaller objects and may not be able to discriminate multiple objects. Higher frequencies will detect smaller and multiple objects, but only at shallower depths, and may miss deeper objects. Use both low and high transducer frequencies for best advantage. US has a unique set of limitations. Areas with many echogenic structures, such as calcifications, sesamoid bones, and tendons, may hide Tintinalli_Sec06_p0267-0328.indd 312 8/2/19 7:16 PM CHAPTER 45: Soft Tissue Foreign Bodies 313 FIGURE 45-8. (Continued) Tintinalli_Sec06_p0267-0328.indd 313 8/2/19 7:16 PM

 MAGNETIC RESONANCE IMAGING MRI can detect nonmetallic radiolucent foreign bodies and, in com parison studies, is more accurate (less sensitive than US but fewer falsepositive interpretations) than any other modality in identifying wood, plastic, spines, and thorns. 3,19,54 MRI should not be used with gravel or metal-containing foreign bodies because ferromagnetic streaks obscure visualization. MRI may provide more information than CT about the position of a foreign body relative to (and its effects on) nearby structures, such as tendons, neurovascular bundles, joints, and muscles.  FLUOROSCOPY Bedside fluoroscopy accurately detects radiopaque (metal, gravel, glass, and pencil graphite) foreign bodies as small as 3 mm. 55,56 Using fluoroscopy to accurately detect glass foreign bodies can be accomplished in transducer will locate foreign bodies that are as deep as 10 cm, a 5-MHz transducer at depths of approximately 7 cm, a 7.5-MHz transducer at depths of 5 cm, and a 12.5-MHz transducer at depths of 2.0 to 0.2 cm. Conversely, the resolution of the image—ability to distinguish two adjacent objects and detect small objects—is greatest with higher frequencies. Thus, low frequencies can detect larger objects at greater depth but may miss smaller objects and may not be able to discriminate multiple objects. Higher frequencies will detect smaller and multiple objects, but only at shallower depths, and may miss deeper objects. Use both low and high transducer frequencies for best advantage. US has a unique set of limitations. Areas with many echogenic structures, such as calcifications, sesamoid bones, and tendons, may hide Tintinalli_Sec06_p0267-0328.indd 312 8/2/19 7:16 PM CHAPTER 45: Soft Tissue Foreign Bodies 313 FIGURE 45-8. (Continued) Tintinalli_Sec06_p0267-0328.indd 313 8/2/19 7:16 PM 314 SECTION 6: Wound Management a brief training session. 57,58 Advantages are convenience, reduced cost, shortened ED time, and, if done with brief intermittent imaging and appropriate shielding, less radiation exposure than CT. An important limitation is that the body part must be able to fit within the fluoroscopic beam path and be thin enough that a viewable image can be obtained. For most adult patients, this limits fluoroscopy to the limbs. Fluoros copy can be used to assist foreign body removal by helping guide the instrument, as the body part (usually extremity) can be rotated during fluoroscopic imaging to provide a real-time, three-dimensional view of the object relative to the physician’s instruments, skin surface, or skin markers. 55,56 An incision is made between needles or markers, or dis section is carried along the path of the closest needle. Safe and effective metallic foreign body extraction under fluoroscopic guidance and local anesthesia is possible (outside of the ED) even when objects are in close proximity to important vessels. GENERAL TREATMENT PRINCIPLES Once a soft tissue foreign body is discovered, weigh the risk of leav ing the foreign body in place against the potential harm of attempting to remove it. Not all foreign bodies must be removed, and not all that require removal must be extracted in the ED. General indications for foreign body removal include potential for later infection, toxicity, injury, and functional problems ( Table 45-2). Usually, objects that are small, inert, deeply embedded, and causing no symptoms can be left in place. Bullets that come to rest deep within a muscle belly are usually not removed because the procedure can cause more damage than leaving the foreign object in place. However, projectiles may drag bits of clothing or skin into the wound, so the entrance wound deserves cleaning and debridement. Bullet migration and embolization are rare but possible complications. Bullets near vessels can enter the systemic circulation. Bullets that cause distal ischemia, thrombus formation, or wall erosion or that lie within the lumen of a blood vessel require immediate removal in the operating room. Thorns, spines, wood splinters, and other vegetative materials should be promptly removed because they cause intense and excessive inflam mation. Foreign objects that are heavily contaminated, such as fractured teeth and soil-covered objects, should be removed as soon as possible. Antibiotic treatment cannot replace foreign body removal. Glass, metal, and plastic are relatively inert, and removal can be postponed, if neces sary. Glass foreign bodies in hands or feet can cause persistent pain with gripping or walking, and they can sever nerves or tendons years after the initial injury. Patients with deep, sharp foreign bodies in these locations should be referred to appropriate specialists for eventual removal. Sometimes, harmless foreign bodies are psychologically distressing to patients, particularly when they are visible under the skin surface or produce a lump. Patient concern may be a justification for elective removal. In general, recommended techniques for soft tissue foreign body removal are based on clinical experience. 61,62 Successful removal of foreign bodies requires adequate local or regional anesthesia and good lighting. Depending on location and depth, tourniquet control of bleeding and assistance may be needed.

ve removal. In general, recommended techniques for soft tissue foreign body removal are based on clinical experience. 61,62 Successful removal of foreign bodies requires adequate local or regional anesthesia and good lighting. Depending on location and depth, tourniquet control of bleeding and assistance may be needed. Depth and accessibility of the object TABLE 45-2 Indications for Foreign Body Removal •  Potential  for inflammation or infection •  Vegetative  or chemically reactive material •  Heavy  bacterial contamination (e.g., teeth, soil) •  Proximity  to fractured bone •  Established  infection •  Allergic  reaction •  Potential  for toxicity, as with heavy metals •  Spines  with venom •  Impingement  on nerves, vessels, or tendons •  Intra-articular  or intravascular location and physician time are the limiting factors for removal of foreign bodies by the emergency physician. Foreign bodies buried deeply in adipose tissue or muscles are difficult to locate. Although most foreign bodies in hands should be removed because the hand is mobile and sensitive, deep exploration of the hand by the emergency physician is not recom mended because knowledge and experience are needed to avoid injury to numerous closely spaced vital structures. The “no man’s land” of the hand (see Figure 268-10 in Chapter 268, “Injuries to the Hand and Digits”) should not be explored. In a busy ED, it may only be possible to devote 15 to 30 minutes to a removal procedure, particularly when other patients demand atten tion. This amount of time is sufficient for locating most foreign bodies. Inform the patient before the procedure that the duration of the exploration will be limited and a best effort will be made to locate and remove the foreign body. If unsuccessful, referral to an appropriate specialist will be made.  POSTREMOVAL TREATMENT After removal of a foreign body, irrigate the wound thoroughly with standard wound irrigation techniques (see Chapter 40, “Wound Prepa ration”). A puncture wound is difficult to clean adequately because either the small wound diameter prevents the irrigation fluid from reaching the wounded tissue or the fluid enters the wound but does not completely drain (see Chapter 46, “Puncture Wounds and Bites”). In general, if the puncture site is contaminated, the entrance wound can be enlarged to allow more effective cleaning, and if foreign debris is impregnated in tissue, the contaminated area can be debrided or excised. If multiple radiopaque or US-visualized objects were removed, or if there are concerns about fragmentation of foreign bodies with rem nant material in the wound, consider repeat radiography or US. The decision to close lacerations, incisions, and block excisions depends on the potential for infection. Wounds in which all foreign contaminants can be removed and those in locations with good blood supply can be closed primarily. Otherwise, delayed primary closure is preferred. Provide necessary tetanus immunization. There is no proven benefit for prophylactic antibiotics for uninfected wounds containing foreign bodies. 63 Antibiotics are justified for infected wounds, particu larly when removal must be postponed. If a foreign body is deliberately left in place, inform the patient of the proposed plan and necessary follow-up. If foreign material was removed, warn the patient that there is always a possibility that not all pieces were found despite careful exploration and imaging studies.  DELAYED REMOVAL Refer patients to surgeons or interventional radiologists for delayed removal of foreign bodies. 64-66 Inform the patient that the object is present but unlikely to cause harm before it is removed.

is always a possibility that not all pieces were found despite careful exploration and imaging studies.  DELAYED REMOVAL Refer patients to surgeons or interventional radiologists for delayed removal of foreign bodies. 64-66 Inform the patient that the object is present but unlikely to cause harm before it is removed. If a foreign body is near a joint or highly mobile region, the affected area should be splinted before removal to prevent further injury or migration of the object. Patients may also present late (>1 week after injury) to the ED for removal of a soft tissue foreign body. Evidence supports use of US for locating and removing soft tissue foreign bodies <30 mm from the skin surface, even in patients who delay seeking care for a penetrating soft tissue foreign body. SPECIFIC FOREIGN BODIES AND REMOVAL PROCEDURES  METALLIC NEEDLES Long, thin foreign bodies, such as sewing and hypodermic needles, may be difficult to locate in soft tissue. There are several techniques avail able for removing needles that are parallel to the surface of the skin. If the needle is superficial enough to be palpable, make an incision at one end to expose and grasp it with a hemostat. The US probe can be used to locate the long axis of the foreign body; an incision is then made at the end closest to the skin, and the needle is grasped with forceps and removed with traction in the direction of the long axis. 68 If the Tintinalli_Sec06_p0267-0328.indd 314 8/2/19 7:16 PM

e and grasp it with a hemostat. The US probe can be used to locate the long axis of the foreign body; an incision is then made at the end closest to the skin, and the needle is grasped with forceps and removed with traction in the direction of the long axis. 68 If the Tintinalli_Sec06_p0267-0328.indd 314 8/2/19 7:16 PM CHAPTER 45: Soft Tissue Foreign Bodies 315 needle is deep, make an incision perpendicular to the needle at its mid point, where it can be clamped with a hemostat and pushed out of the entrance of the original wound (Figure 45-9). Sometimes application of an industrial magnet may attract the foreign body to the magnet for removal. After locating the area of greatest attraction, the overlying skin is prepared and anesthetized, and a small incision is made at the site. The magnet is then placed over the incision to attract the metallic foreign body and remove it from the soft tissue by pulling the magnet away from the incision site. Do not apply magnets in patients with pacemakers or implanted defibrillators. Long, thin foreign bodies that are oriented perpendicular to the skin surface can be elusive. If a needle or nail can be reached with an alligator forceps or hemostat, it can be pulled straight out. If a needle lies beyond the reach of an instrument, the entrance wound can be enlarged with a skin incision (Figure 45-10). However, the incision may easily pass to the side of the object, so undermine the skin edges and apply pressure on the skin edges that will displace the foreign body into the center of the wound, where it can be seen and grasped. Once removed, the needle and the wound should be inspected to ensure that the object was removed in its entirety.  WOOD SPLINTERS AND ORGANIC SPINES Solid foreign bodies can be pulled out of puncture wounds with forceps, but wood splinters and organic spines (e.g., cactus, sea urchin, and fish) may disintegrate with this technique. Only superficial splinters that are a few millimeters long can be grasped and removed with a fine-point splinter forceps. A splinter parallel to the skin surface should be lifted out of the wound after incising the skin along the long axis of the object. If the splinter is lodged in the subcutaneous tissue, the entrance wound should be enlarged with a skin incision so the foreign body can be grasped under direct visualization. Occasionally, foreign bodies migrate from their initial entrance site. If the original entrance is incised in this situation, additional tissue dissection may be required. Ultrasonography can be used to confirm the current location of the foreign body and to determine its longitudinal axis. An incision can then be made at the end of the object nearest the skin surface. Wood fragments may be impossible to locate precisely. One solution is to create an elliptical incision around the puncture wound and extract the fragment in a block of tissue (Figure 45-11). Avoid incorporating nerves, vessels, or tendons within the excised block. Either technique creates a larger wound, but allows a better inspection and more thor ough cleaning after removal. Subungual splinters should be removed because of the risk of subse quent infection with the possibility for distal phalanx osteomyelitis. If the splinter is underneath the distal end of the nail, it can be grasped by a splinter forceps or hooked by a hypodermic needle bent at its tip. More proximal splinters can be reached by anesthetizing the finger and removing a wedge of the nail overlying part of the foreign body (Figure 45-12). If there are multiple splinters, the entire nail can be removed in one piece, the foreign bodies extracted, and the nail placed back under the cuticle and tacked down on to the nail bed (see Chapter 43, “ Arm, Forearm, and Hand Lacerations”).

moving a wedge of the nail overlying part of the foreign body (Figure 45-12). If there are multiple splinters, the entire nail can be removed in one piece, the foreign bodies extracted, and the nail placed back under the cuticle and tacked down on to the nail bed (see Chapter 43, “ Arm, Forearm, and Hand Lacerations”). Numerous, tiny cactus spines in the dermis can be plucked out indi vidually with forceps or extracted together with depilatory wax, profes sional-quality facial gel, rubber cement, or household glue. Larger spines and thorns should be removed with incision or excision techniques.  FISHHOOKS Fishhooks have a variety of sizes and shapes based on a common pat tern (Figure 45-13). The barb, which is a projection extending backward from the point of the hook, keeps the point embedded in the fish’s mouth and makes removal from skin a challenging task. Most fishhook injuries involve the hands, head, or face. There are several methods for removing fishhooks embedded in skin. 71 The best strategy depends primarily on the depth of the hook. If the hook has multiple barbs, take precautions to avoid impaling the treating physician, bystanders, or the patient (a second time) during removal by taping or cutting off the exposed barbs. With any technique, the skin should be cleaned and anesthetized at the entry site. If the hook is superficial, use the retrograde technique by applying gentle downward pressure on the shank while the hook is simply pulled back out along the path of entry (Figure 45-14). (See Video: Fishhook and Taser Removal.) The needle-cover technique is commonly described but rarely suc cessful. The technique requires physician dexterity and is useful only if the hook is superficial. Insert an 18-gauge needle into the entrance wound alongside the shank of the hook. Have the needle follow the bend of the hook until the lumen of the needle can be placed over the barb to sheathe it. The hook and needle are then withdrawn from the wound as a unit (Figure 45-15). FIGURE 45-9. A. An incision is made perpendicular to the needle at its midpoint. B. The needle is grasped through the incision with a hemostat and backed out of the puncture wound. Incise Undermine Press downward AB C FIGURE 45-10. A. The entrance site is enlarged with a skin incision. B. If the incision passes to the side of the object, the skin is undermined. C. Pressure on the skin edges displaces the foreign body into the center of the wound. Tintinalli_Sec06_p0267-0328.indd 315 8/2/19 7:16 PM

ncise Undermine Press downward AB C FIGURE 45-10. A. The entrance site is enlarged with a skin incision. B. If the incision passes to the side of the object, the skin is undermined. C. Pressure on the skin edges displaces the foreign body into the center of the wound. Tintinalli_Sec06_p0267-0328.indd 315 8/2/19 7:16 PM 316 SECTION 6: Wound Management Eye Shank Point Bend Throat Gap Barb FIGURE 45-13. Anatomy of a fishhook. Push Push FIGURE 45-14. Simple retrograde technique for fishhook removal. While pressing the skin over the tip of the hook to disengage the barb and applying gentle downward pressure on the shank, back the hook out of the skin. If the barb catches on skin fibers, other techniques must be used. FIGURE 45-15. Needle-cover technique for fishhook removal. The area is anesthetized, and an 18-gauge needle is inserted into the entrance wound along the hook. The lumen of the needle is placed over the barb to cover it, and both the hook and needle are backed out of the wound. Splinter forceps Subungual foreign body Wedge excision of nail FIGURE 45-12. Subungual foreign bodies that are beyond the reach of a splinter for ceps can be exposed by excising a wedge of the overlying nail. AB C FIGURE 45-11. Block excision is effective for foreign bodies that are friable, difficult to find, buried in fatty tissue, or stain surrounding tissue. A. A small, elliptical incision is made around the original wound. B. The incision is undercut until contact is made with the foreign body. C. The block of tissue is grasped with a forceps, the foreign body is clamped with a hemostat, and both are removed. Tintinalli_Sec06_p0267-0328.indd 316 8/2/19 7:16 PM