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11.08 Subcutaneous foreign body


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:

What not to do:

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:


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from Buttaravoli & Stair: COMMON SIMPLE EMERGENCIES
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