11.08 Subcutaneous foreign body

agk’s Library of Common Simple Emergencies

Presentation

Small, moderate-velocity metal fragments can be released when a hammer strikes a second piece of metal, such as a chisel. The patient has noticed a stinging sensation and a small puncture wound or bleeding site, and is worried that there might be something inside. BB shot will produce a more obvious but very similar problem. Another mechanism for producing radio-opaque foreign bodies includes punctures with glass shards, especially by stepping on glass fragments or receiving them in a motor vehicle accident. Physical findings will show a puncture wound and may show an underlying, sometimes palpable, foreign body.

What to do:

• Be suspicious of a retained foreign body in all wounds produced by a high velocity missle or sharp fragile object. The most common error in the management of soft tissue foreign bodies is failure to detect their presence.
• X ray the wound to document the presence and location of the suspected foreign body. Explain how difficult it often is to remove a small metal fleck, and that often these are left in without any problem (like shrapnel injuries).
• Inform the patient that, since it is best to remove the foreign body, you will attempt a simple technique, but that in order to avoid more damage, you will not extend your search beyond 15-30 minutes.
• If the foreign body is in an extremity, then it is preferable, and sometimes essential, to establish a bloodless field.
• Anesthetize the area with a small infiltration of l% Xylocaine with epinephrine (avoid tissue swelling, and do not use epinephrine on digits).
• Take a blunt stiff metal probe (not a needle) and gently slide it down the apparent track of the puncture wound. Move the probe back and forth, fanning it in all directions, until a clicking contact between the probe and the foreign body can be felt and heard. This should be repeated several times until it is certain that contact is being made with the foreign body.
• After contact is made, fix the probe in place by resting the hand holding the probe against a firm surface and then, with your other hand, cut down along the probe with a #15 scalpel blade until you reach the foreign body. Do not remove the probe.
• Reach into the incision with a pair of forceps and remove the foreign body (located at the end of the probe).
• Close the wound with strip closures or sutures.
• If the track is relatively long and the foreign body is very superficial and easily palpable beneath the skin, then it may be advantageous to eliminate the probe and just cut down directly over the foreign body.
• Provide tetanus prophylaxis.
• Warn the patient about signs of developing infection.
• If you are unable to locate the foreign body in 15-30 minutes, inform the patient that in the case of a small metal fleck, the wound will probably heal without any problem. It may migrate to the skin surface over a period of months or years, at which time it can be more easily removed. Should the wound become infected, it can be successfully treated with an antibiotic, and the foreign body can be more easily removed if a small abscess forms. Patients with glass, sea shell fragments, gravel or other potentially harmful objects imbedded subcutaneously should have them removed as soon as possible, and will require surgical consultation or referral.
• Always provide the patient with a physician who can perform the necessary followup care.
• Schedule a wound check within 48 hours or warn the patient about signs of infection.

What not to do:

• Do not cut down on the metal probe if there is any possibility of cutting across a neurovascular bundle, tendon or other important structure.
• Do not attempt to cut down to the foreign body, unless it is very superficial, without a probe in place and in contact with the foreign body.

Discussion

Moderate-velocity, metallic foreign bodies rarely travel deeply into the subcutaneous tissue, but you must consider a potentially serious injury when these objects strike the eye. A specialized orbital CT scan should be obtained in these cases. With simple penetration, x rays are needed to document the presence of a foreign body and its location relative to significant anatomic structures. X rays are usually of little value, though, in accurately locating metalic flecks. Even when skin markers are used, because of variances in the angle of the x ray beam to the film, relative to the skin marker and foreign body, the apparent location of the foreign body is often significantly different from the real location. An incision made over the apparent location, therefore, usually produces no foreign body. Needle localization under fluroscopy may be required for those objects that must be removed and the simple probe technique described above fails to deliver the foreign body. If you are attempting to remove a metallic object and you have a strong eye magnet available, it can be substituted for the probe described above. First, enlarge the entrance wound and then, after contact with the magnet, the object can be dissected out or even pulled out with the magnet. Almost all glass is visible on plain x rays, but small fragments, between 0.5 and 2.0mm, may not be visible, even when left and right oblique projections are added to the standard posterior-anteroir and lateral views. Any patient who complains of a foreign body sensation should be assumed to have one even in the face of negative x rays.

References:

• Courter BJ: Radiographic screening for glass foreign bodies--what does a “negative” foreign body series really mean? Ann Emerg Med 1990;19:997-1000.
• Schlager D, Sanders AB, Wiggins D, et al: Ultrasound for the detection of foreign bodies. Ann Emerg Med 1991;20:189-191.
• Ginsburg MJ, Ellis GL, Flom LL: Detection of soft-tissue foreign bodies by plain radiography, xerography, computed tomography and ultrasonography. Ann Emerg Med 1990;19:701-703.
• Montano JB, Steele MT, Watson WA: Foreign body retention in glass-caused wounds. Ann Emerg Med 1992;21:1360-1363.

-----------------------------------------------------
from Buttaravoli & Stair: COMMON SIMPLE EMERGENCIES ©
Longwood Information LLC 4822 Quebec St NW Washington DC 20016-3229
1.202.237.0971 fax 1.202.244.8393 electra@clark.net
-----------------------------------------------------