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 chedk 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 specialize orbital CT scan should be obtained in these cases. Wiuth 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: Detecction 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.
