Wound Care: Foreign bodies in the skin 
Jill E. Winland-Brown EdD, MSN, FNP-BC 
Sandra Allen MSN, FNP-BC 

The Nurse Practitioner: The American Journal of Primary Health Care
June 2010 
Volume 35 Number 6
Pages 43 - 47

A foreign body in the skin is retained material that can originate from numerous sources and may result in soft tissue injury. These injuries range from something as simple as a small splinter, which requires nothing more than a needle and tweezers for removal at home, to others that can cause toxic and allergic reactions, inflammation, or infection, requiring antibiotics or even surgery for removal.

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Foreign bodies can be extremely diverse, from thorns of plants or trees to glass shards embedded in the skin from a car crash or even slivers of metal and gravel. They can also be animal-based, obtained from the penetration of fish spines or larvae that burrow into human skin. The risk of such injuries is heightened during the summer and in warm climates when individuals go barefoot and engage in more outdoor activities.1

Clinical presentation

All wounds that penetrate the skin need to be evaluated for embedded material. A thorough history of how the wound occurred is important, as is identifying the foreign body. The mechanism of wounding can help determine the likelihood of deep structure injury and associated injuries. For example, a dental injury following a blow or punch to the mouth should lead the practitioner to suspect fragments of teeth may be embedded in the patient's lip or tongue. Additionally, tooth fragments may be embedded in the hand of the individual who delivered the punch.1 For new injuries, bleeding may be present, and the foreign body may still be visible. In older injuries, the foreign body may be embedded, and the surrounding skin may be indurated and inflamed.

Patients with retained foreign bodies may present after the wound heals, experiencing sharp pain with movement or pressure over the site. Discoloration or a visible mass under the epidermis may facilitate the diagnosis. When a mass cannot be visualized, it can sometimes be palpated. Sharp, localized pain with palpation over a puncture wound may indicate a retained foreign body. If there is limited passive range of motion of a joint near a wound, a foreign body should be suspected. Other indications of a foreign object include the following:

* A wound with persistent purulent drainage or a chronic draining sinus may indicate an old wound with a retained foreign body.

* A sterile abscess that impairs wound healing may result from a foreign body.

* Sudden, local inflammation may indicate an allergic reaction caused by the embedded material.

* A wound that fails to heal or does not respond to antibiotic therapy may indicate the presence of a retained material.

A wound caused by objects that shatter or splinter may have fragments embedded in it.1 Sharp wooden branches and thorns are usually very brittle and may cause deep puncture wounds. These wood splinters may frequently break into small pieces when pulled from a puncture wound. Retained foreign bodies may result in chronic, delayed, or recurrent infections.

Patients pierced by a thin metal object such as a sewing needle may think they have removed the needle, when actually a piece of the needle may have broken off and remains underneath the skin's surface. Fragments of a needle can result in persistent pain or even an abscess.

There may be other materials embedded in the skin besides the offending agent. If a nail penetrates both the shoe and the sock, it may also force leather, rubber, or sock material into the foot. A blunt object may push a plug of epidermis deep into the dermis. This traumatic implantation results in an epidermal inclusion cyst.2


A thorough medical history should be obtained. Patients with diabetes or a history of vascular problems have a higher potential for acquiring an infection.3 To assess penetrating wounds, the following four "P"s should be used: pain, pulselessness, parasthesia, and pallor.

As pain is very subjective, it is difficult to assess. If pain is present when palpating over the offending foreign body, the foreign body must be removed. Deep or perpendicular splinters are painful to pressure. Wounds should be assessed before anesthesia by palpating over the injury and margin of the wound to determine whether the patient can feel a foreign body in the wound.

Pulselessness is caused by a foreign body exerting pressure on an artery. Assess the extremity distal to the wound to check for pulses. For fingers and toes, check for the capillary refill time-a normal blanch response is less than 2 seconds.

Patients may experience paresthesia, a subjective reporting of numbness or tingling ("pins and needles"), with decreased sensation as a result of a foreign body pressing against nerves. Any wound to an extremity needs to be evaluated for distal circulation and sensation, as distal sensation can rule out nerve injury.

Pallor will occur from pressure of the foreign body against blood vessels. Occlusion of the blood vessels may result in the surrounding tissues becoming anoxic and even necrotic if severe and left untreated.

Diagnostic tests

Accurate localization of a foreign body before removal is imperative because blindly searching for the object may cause additional injury. Suspect a retained foreign body in wounds deeper than 5 mm, in wounds whose depth cannot be visualized, and in infected wounds.1 There are many diagnostic tests to determine the placement of a foreign body in the skin, including X-ray, computed tomography (CT) scan, ultrasonography, and magnetic resonance imaging (MRI).

X-ray. Foreign bodies not visible to the eye during initial evaluation may be identified by an X-ray, which may also be necessary to pinpoint the exact location for removal. Metal, aluminum, bone, some types of fish spines, teeth, graphite (from pencils), some types of plastics, glass, gravel, stone, wood, and sand, are visible on plain X-ray.1 A plain film should also be ordered first if a suspected foreign body is not found during exploration of the wound.

Plain films should be obtained with an underpenetrated soft tissue technique, which produces a lighter film and improves the contrast between the foreign body and surrounding tissue.1 The practitioner needs to be very astute to detect small and faint foreign bodies. Plain films, taken in multiple projections, help to distinguish the shadow of the foreign body from underlying bone and may help determine the depth of the object in the tissue. Multiple projections can also be used to help estimate the location of the foreign body after placement of radiopaque skin markers, such as paper clips, on the skin at the wound site.

CT scan. A CT scan is more sensitive than plain-film X-ray and is able to detect multiple types of foreign material. The disadvantages of CT are its cost and increased radiation dose. CT scan is usually reserved for failed exploration or infection.1

Ultrasonography. An ultrasonography is often used to detect wooden, plastic, and radiolucent foreign bodies.4 It can also detect soft tissue foreign bodies that are larger than 4 to 5 mm, such as wood, fish bones, other organic material, fiber, and some plastics. Ultrasonography has a sensitivity of 50% to 90% and may be used to estimate the depth and size of a foreign body as well as determine its relationship to surrounding anatomic structures.1

MRI. An MRI can detect nonmetallic foreign bodies. However, it should not be used to detect gravel or metal-containing foreign bodies. As with the CT scan, the main disadvantage is its high cost.

Management of the injury

The wound should be visually inspected thoroughly whenever possible during cleaning. Adequate lighting, good hemostasis, access to local anesthesia, and patient cooperation are essential. In the practitioner's office, the most effective way to lower the bacterial count is with a high-pressure irrigation of 0.9% sodium chloride or tap water. Large data-based studies (Level 1 or A) show that antiseptic solutions should not be used for cleansing foreign body wounds because they slow healing.1 Povidone iodine (Betadine) or peroxide solution can be toxic to lacerated tissue.3

Once a soft tissue foreign body is identified, the practitioner needs to weigh the risk of leaving the foreign body in place against the potential harm of removal. Not all foreign bodies must be removed, but should be if there is pain. Other indications that support removal include potential for infection, toxicity, injury, or functional limitations.

The decision to remove a foreign body that is deeply embedded in the skin depends on the object's size, location, composition, accessibility, and any anticipated mechanical and inflammatory effects. Wood splinters, thorns, and other vegetative materials require immediate removal because they may produce intense inflammation. Other foreign bodies that are heavily contaminated, such as tooth fragments and soil-covered objects, should be removed as soon as possible. Removal of inert objects such as glass or metal may be delayed if necessary. However, most foreign bodies in the hands should be removed, and deep foreign bodies in the hands and feet or face should be referred to a specialist for removal because of the potential risk of nerve and tendon injury.

For deeper embedded objects, the wound needs local or regional anesthesia and should be assessed under a bright light. Local anesthetics that contain epinephrine should not be used on the fingers or toes due to potential constriction of end arterioles. If the 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.

Visualization may be difficult when assessing punctures and other narrow wounds or if a foreign body is below the surface. Typically, these wound margins should be extended with a scalpel; however, deep wounds are difficult to explore and can hide foreign material easily. Blind probing of the narrow wound with a hemostat may cause further tissue damage and nerve or vascular injury. This technique should only be done if extending the wound is not the preferred technique.

The wound edges should be retracted gently to minimize tissue trauma. Using a forceps with teeth or tissue retractors, the NP should hook the wound edge and retract it to expose the foreign body in deeper tissues. The wound can then be probed by hand.3 If any object pulled from a wound does not appear intact, the wound should be explored for further contaminants. This technique can be especially dangerous in wounds of the hands, feet, or faces. Direct visualization by a specialist is the preferred method of exploration.

Sutures may be required depending on the size of the incision and the amount of probing necessary. Suture material should be appropriate for the site, with 3-0 or 4-0 nylon for lower extremities, 4-0 nylon for the hand, and 5-0 nylon for the face. To avoid obvious scars and poor cosmetic results, the edges must be meticulously aligned and slightly everted. The length of time the sutures are left in place depends on the site because if they are left in too long, scarring can result. Recommended times for suture removal are face, 4 to 6 days; trunk, 7 to 10 days; extremities, 10 to 14 days; and joints, 14 days.3 Steri strips can be applied to reinforce the wound and prevent tension on the wound edges.

Many patients worry that a pencil puncture wound could cause lead poisoning. Assure them that pencils are made with graphite and clay instead of lead. Occasionally the graphite dust may leave a tiny black stain called a traumatic tattoo in the wound, but the patient will not be harmed.

After care

The wound should be kept clean and dry and covered with a fresh bandage daily. For sites that are difficult to keep bandaged, a thin layer of antibiotic ointment may be used to provide protection. Transient inflammation is a normal part of wound healing, but when there is significant amount of devitalized tissue, foreign debris, or bacteria present within a wound, this protective inflammatory response is intensified.

If the foreign body was dirty or saliva was involved, a tetanus immunization is needed. Tetanus prophylaxis should be given within 72 hours of the injury; most providers will recommend tetanus prophylaxis if 5 years have elapsed since the last immunization.

Infections are the most common complication of retained foreign bodies, even when the foreign material itself is not contaminated. Antibiotic prophylaxis isn't necessary for most minor soft tissue foreign bodies that have been removed as the wound will usually resolve spontaneously after it is well-irrigated and cleansed. A clean wound in a well-vascularized area has a 3% to 5% chance of becoming infected, and nonorganic slivers, such as metal or glass, generally do not become infected.5 The source of the foreign body determines whether antibiotics are necessary. Contaminated, dirty wounds or wounds that involve areas of diminished vascular supply, such as fingers, toes, and ears, usually need antibiotics. Organic slivers, such as wood or thorns, can become infected if they are not removed. Amoxicillin clavulanate (Augmentin), cephalexin (Keflex), or cefadroxil (Duricef) can be prescribed. If the patient is allergic to penicillin or cephalosporins, doxycycline (Vibramycin), with or without clindamycin (Cleocin) or ciprofloxacin (Cipro), may be prescribed. Special consideration should be given to immunocompromised patients as they are at greater risk for infection, especially those exposed to a possible fungal infection caused by a vegetative foreign body. Oral ketoconazole (Nizoral) should be used for a fungal infection.

Foreign bodies may incite a variety of soft tissue infections, including local wound infection, cellulitis, abscess formation, lymphangitis, tenosynovitis, bursitis, and osteomyelitis. These infections are characteristically resistant to therapy. Antibiotics, anti-inflammatory drugs, and corticosteroids may produce a partial regression of symptoms, but seldom eradicate the infection.

Patients should be monitored and followed up for any retained foreign bodies to determine potential need for future extraction.

Special cases

Punctures by fish spines and marine invertebrates may introduce Vibrio vulnificus, a virulent waterborne Gram-negative bacteria, which presents as rapidly progressing cellulitis with edema and hemorrhagic bullae; it may progress to necrotizing fasciitis.6 Assess the patient for lymphatic streaking (see Example of lymphatic streaking). Removal of the foreign body and aggressive irrigation of the wound should precede consultation with an infectious medicine specialist, as the patient may require hospitalization and I.V. antibiotics.

Swimmers and divers may step on sea urchins, which break off at the insertion point and are both fragile and difficult to remove. Sea urchin spines and catfish spines contain venom that causes severe burning pain at the puncture site. Anecdotal remedies include the use of a paste made from meat tenderizer.7 The papain in the meat tenderizer is thought to dissolve the foreign protein of the sea urchin spines. If the area becomes inflamed further, a mid-strength topical corticosteroid cream (triamcinolone 0.1% [Kenalog]) may be applied twice daily for 1 week. The soles of the feet and the palms of the hands are thick, so the topical corticosteroid (clobetasol [Cormax]) may be used in these areas. Chronic inflammation with granuloma formation may occur.

Patients may also present with what looks like a boil-like lesion that is not responsive to antibiotics and experience a sensation of movement in the skin. Assess the patient for recent travel to Central America or South America as Dermatobia hominis, otherwise known as the human botfly that lives at the edge of tropical forests. The botfly egg hatches rapidly on the skin, and the larva burrows into the skin where it feeds on soft tissue. Larval growth causes an abscess-like lesion with a central pore through which the larva breathes.8 To remove the D. hominis larva, occlude the pore with mineral oil or petrolatum and apply lateral pressure. If this is not effective, anesthetize the area, use a 4-mm punch, and manually remove the larva. Complete removal is necessary as remaining larval parts may induce a foreign body reaction.9 Irrigate the defect thoroughly, do not suture, and apply a bandage. The defect will heal by secondary intention and antibiotics are usually not necessary.

Figure. Example of g... - Click to enlarge in new window Figure. Example of granulomas

Cutaneous larva migrans is an infection caused by infected larva of the hookworm, and presents as severely pruritic, with an elevated tunnel, or thread-like lesions. It is contracted by walking barefoot in soil contaminated by animal feces.10 Treatment includes antihelminthic medications, including albendazole (Albenza), ivermectin (Stromectol), and thiabendazole (Mintezol), but the disease is self-limiting in humans and usually resolves within weeks.10

Foreign bodies left in wounds may work their way to the surface and can be easily removed. Granulomas may form when the body attempts to wall off a retained foreign body, and may present as indurated tumors or nodules or as small pustules (see Example of granulomas). Anesthetize the area with the appropriate local anesthetic if necessary and remove the foreign body. Suture the wound as needed; antibiotics are not needed unless signs of infection are present.


Patients may shower after 12 hours, but should not submerse the wound in water until the sutures, if any, are removed. The wound should be cleaned daily with warm soapy water. Detailed wound-care instructions should be given to patients with open wounds. Patients should be instructed to watch for any signs of infection that warrant a return visit, such as redness, increased pain, swelling, fever, red streaks progressing up the extremity, or any purulent discharge.3

Many patients must be referred to surgical specialists for delayed removal of foreign bodies. It is important to inform the patient that the object is present but unlikely to cause harm before it is removed.


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