Chapter 45: Soft Tissue Foreign Bodies

Soft tissue foreign bodies may be encountered when managing new wounds or evaluating complications of old wounds. This chapter discusses methods of detecting and removing them.

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 decision 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.³

Transient inflammation is an integral part of normal wound healing. A small amount of foreign debris in a wound provokes an inflammatory 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 encapsulated, 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 inflammation. The oils and resins in redwood and cedar splinters also cause considerable inflammation. Sea urchin spines and catfish spines contain 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.^4,5

Infections are the most common complication of retained foreign bodies, producing local wound infection, cellulitis, abscess formation, lymphangitis, tenosynovitis, bursitis, septic arthritis, and osteomyelitis.^6,7 Infections associated with retained soft tissue foreign bodies are characteristically resistant to therapy; antibiotics, anti-inflammatory drugs, and steroids may produce a partial regression but seldom eradicate the infection.⁸ Some infections will resolve spontaneously 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, Pantoea agglomerans is the most commonly reported isolate.^9,10 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.

HISTORY

Every wound has the potential for concealing a foreign body, but only a small percentage of lacerations and puncture wounds actually contain them.^1,2,11 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.^12,13,14 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 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.¹¹ However, foreign body sensation is less useful in verbal-age children.¹⁵ 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 pressure over the site. Failure of a wound to heal also may be evidence of a retained irritant. Chronic, delayed, and recurrent infections are associated 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.^7,8 Unsuspected foreign bodies may present as soft tissue masses.¹⁶

PHYSICAL EXAMINATION

Physicians are occasionally surprised by foreign bodies that are embedded 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 well-localized 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.^1,2,11 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. 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).

Wounds that penetrate deeply into adipose tissue are difficult to explore and easily hide foreign material. Blind and 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 puncture wounds caused by nails and to search for clear glass, which is difficult 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 dangerous in hands, feet, or face, where direct visualization is the preferred method of exploration.

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.^3,17 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.¹⁸ 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).^3,18 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.¹⁹ 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. 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.^11,15,17 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 radiography, like wood, sonography is the modality of choice, with CT or MRI as alternatives.¹⁸ The bottom line is that 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 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).²⁴ 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.^3,18,25 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.

CT

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).¹⁸ 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.¹⁸ Water-rich wood, either fresh from a tree or as occurs when dry wood has been imbedded in tissue long enough to absorb serohematic fluid, is more visible as a slightly hyperdense object on CT.²⁶

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 further 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.²⁷

US

US is useful for directing exploration and foreign body removal.^28,29,30 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 >90% sensitivity for foreign bodies >4 to 5 mm (Figure 45-8).^{31,32,33,34,35,36} Detection rates may be less due to the size and sonographic nature of the foreign body, 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.³⁷ 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.³⁴

With experience, sonography can be applied to body areas previously difficult to image for soft tissue foreign bodies, such as the hands and feet.^38,39,40,41 Soft tissue gas does not appear to reduce the ability to detect a foreign body but does decrease the ability to discriminate between metal and wood.⁴²

An important technical aspect of US for soft tissue foreign body detection is the transducer frequency.⁴³ Higher frequencies have a reduced effective depth of penetration for the US wave. A 3.5-MHz 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 foreign bodies within their acoustic shadows, so these areas must be scanned slowly to detect foreign bodies that are small or oriented perpendicular 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.^{38,39,40,43,44} False-positive findings result in an unnecessary surgical dissection. False-positive rates for sonography vary from 3% to 15% in clinical case series, depending on the material being studied.^34,36,45,46

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.^{28,29,30,38,39} 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 (Figure 45-9). 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.²⁸ The primary advantage of sonography is the avoidance of radiation exposure.

MRI

MRI can detect nonmetallic radiolucent foreign bodies and, in comparison studies, is more accurate (less sensitive than US but fewer false-positive interpretations) than any other modality in identifying wood, plastic, spines, and thorns.^3,18,47 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.^48,49 Using fluoroscopy to accurately detect glass foreign bodies can be accomplished in a brief training session.^50,51 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. Fluoroscopy 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.^48,49 An incision is made between needles or markers, or dissection is carried along the path of the closest needle.

Once a soft tissue foreign body is discovered, weigh the risk of leaving 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 inflammation. 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 necessary. 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.⁵²

The techniques for soft tissue foreign body removal are based on clinical experience; there are no controlled or randomized studies comparing different approaches or techniques.^53,54 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 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 recommended 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 titled "Injuries to the Hand and Digits") should not be explored either.

In a busy ED, it may only be possible to devote 15 to 30 minutes to a removal procedure, particularly when other patients demand attention. 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 Preparation"). 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 objects were removed, obtain a postprocedure plain radiograph.

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.⁵⁵ Antibiotics are justified for infected wounds, particularly 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.^56,57,58 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.

METALLIC NEEDLES

Long, thin foreign bodies, such as sewing and hypodermic needles, may be difficult to locate in soft tissue. Two techniques are available 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. If the needle is deep, make an incision perpendicular to the needle at its midpoint, where it can be clamped with a hemostat and pushed out of the entrance of the original wound (Figure 45-10). Sometimes application of a magnet may attract the foreign body to the magnet for removal. 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 (Figure 45-11). If a needle lies beyond the reach of an instrument, the entrance wound can be enlarged with a skin incision (Figure 45-12). 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 (Figure 45-13). 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. 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 45-14). Avoid incorporating nerves, vessels, or tendons within the excised block. Either technique creates a larger wound but allows a better inspection and more thorough cleaning after removal.

Subungual splinters should be removed because of the risk of subsequent 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 45-15). 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 and Hand Lacerations").

Numerous, tiny cactus spines in the dermis can be plucked out individually with forceps or extracted together with depilatory wax, professional-quality facial gel, rubber cement, or household glue. Larger spines and thorns should be removed with incision or excision techniques.

FISHOOKS

Fishhooks have a variety of sizes and shapes based on a common pattern (Figure 45-16). 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 (Figure 45-17).

There are several methods for removing fishhooks imbedded in skin. 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 45-18).

The string-pull method is a variation on the retrograde technique. Wrap string around the bend of the hook where it enters the skin. Depress the end of the shank with one hand to disengage the barb from deeper tissue. With the other hand, give a quick pull on the string, extracting the hook (Figure 45-19). The disadvantages of this technique are that failure can cause further pain to the patient and success can result in ripped tissue or a sharp, blood-contaminated object flying uncontrollably across the room.

The needle-cover technique is commonly described but rarely successful. The technique requires physician dexterity and is only useful 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 45-20).

The advance-and-cut technique is useful for deeply penetrated and larger fishhooks (Figure 45-21). Advance the tip of the hook through the skin surface. Once exposed, the point and barb are cut with wire cutters, and the remaining part of the hook is rotated back out of the original wound. If barbs along the shank are embedded beneath the dermis, the shank can be clipped near the hook's eye. The remaining part of the hook is then passed antegrade through the skin. The advance-and-cut method traumatizes and contaminates tissue but is an effective method in the ED if the barb has nearly or already penetrated the surface of the skin.

The incision technique is nearly always successful in removing fishhooks. Enlarge the entrance wound 2 to 3 mm with a #11 scalpel blade. Continue the incision along the bend of the hook to the barb until the barb is disengaged from the soft tissue. The hook can then be withdrawn easily through the larger entrance (Figure 45-22). If necessary, the barb can be grasped with a hemostat to prevent it from snagging tissue on the way out. There are two major benefits to enlarging puncture wounds containing foreign bodies. First, the wound is more easily inspected for additional foreign bodies. In the case of fishhook impalement, the wound may be harboring the bait that was on the hook. Second, the wound tract is more easily irrigated through a larger opening. However, the incising scalpel can easily injure tendons, nerves, and vessels.

TRAUMATIC DERMAL TATTOOING

Foreign particulates may be embedded in the epidermal and dermal layers of skin by an abrasion, which permanently stains or "tattoos" the surrounding tissue. If vigorous scrubbing does not remove the particulates, refer the patient to specialists for dermabrasion or block excision. The graphite from pencil lead can produce a pigmentation that may never dissolve; therefore, graphite should be excised in cosmetic areas (Figure 45-23).