10.07 Subungual Hematoma

agk’s Library of Common Simple Emergencies

Presentation

After a blow or crushing injury to the fingernail, the patient experiences severe and sometimes excruciating pain, that persists for hours, and may even be associated with a vaso-vagal response. The fingernail has an underlying deep blue-black discoloration which may be localized to the proximal portion of the nail or extend beneath its entire surface.

What to do:

• X ray the finger to rule out an underlying fracture of the distal phalanx and test for a possible avulsion of the extensor tendon.
• Paint the nail with 10% povidone iodine (Betadine) solution.
• Adhere to universal blood and bodily-fluid precautions (blood is under pressure and may spurt out).
• Perform a trephination at the base of the nail, using the free end of a hot paper clip, electric cauterizing lance or drill. When performed quickly, patients do not feel the heat, just relief from pain. Tap rapidly with the cautery or drill a few times in the same spot at the base of the hematoma until the hole is through the nail. When resistance from the nail gives way, stop further downward pressure to avoid damaging the nail bed.
• Persistant bleeding from this opening can be controlled by having the patient hold a folded 4" x 4" gauze pad firmly over the trephination while holding his hands over his head.
• Apply an antibacterial ointment such as Betadine and cover the trephination with a Band-Aid.
• To prevent infection, instruct the patient to keep his finger dry for 2 days and not to soak it (e.g., go swimming) for 1 week.
• If there is an underlying fracture, instruct the patient to keep his finger as dry as possible for the next ten days and return immediately at the first sign of infection.
• A protective aluminum finger tip splint may also be comforting, especially if the bone is fractured.
• Inform the patient that he will eventually lose his fingernail, until a new nail grows out after two to six months.

What not to do:

• Do not perform a trephination on a subungual ecchymosis (see below).
• Do not perform a trephination using a hot cautery device on a patient wearing artificial acrylic nails, which are flammable.
• Do not perform a trephination when there is an underlying fracture (this theoretically converts a closed fracture to an open one) unless there is sufficient pain to justify it. The patient should also understand the potential risk of developing osteomyelitis, as well as the need for keeping the finger dry.
• Do not perform a digital block. Anesthesia should not be necessary for a simple nail trephination of an uncomplicated subungual hematoma.
• Do not perform a trephination on a patient who is no longer experiencing any significant pain at rest. A mild analgesic and protective splint will usually suffice.
• Do not make such a small opening that free drainage does not occur. The electrocautery tip may have to be bent to the side, widened, or moved around to make a wide enough hole.
• Do not hold a hot paper clip or cautery wire on the surface without applying enough slight pressure to melt through the nail. Just holding the hot tip adjacent to the nail can heat up the hematoma and increase the pain without making a hole to relieve it.
• Do not send a patient home to soak his finger after a trephination. This will break down the protective fibrin clot and introduce bacteria into this previously sterile space.
• Do not routinely prescribe antibiotics. Even when opening a subungual hematoma with an underlying fracture of the distal phalynx, antibiotics have not been shown to be of any value in preventing infection.
• Do not remove the nail even with a large subungual hematoma. It is not necessary to inspect for nailbed lacerations or repair them with a closed injury.

Discussion:

The subungual hematoma is a space-occupying mass that produces pain secondary to increased pressure against the very sensitive nailbed and matrix. Given time, the tissues surrounding this collection of blood will stretch and deform until the pressure within this mass equilibrates. Within 24 hours the pain therefore subsides and, although the patient may continue to complain of pain with activity, performing a trephination at this time may not improve his discomfort to any significant extent and will expose the patient to the risk of infection. If you choose not to perform a trephination explain this to the patient who may be expecting to have his nail drained. There is some risk of missing a nail bed laceration under the hematoma, but, for most underlying lacerations, splinting by its own nail may be superior to suturing. When there are associated lacerations, open hemorrhage or broken nails, a digital block should probably be performed and the nail lifted up for inspection of the nailbed and repair of any lacerations. Keep in mind that not all dark patches under the nail are subungual hematomas. Consider the diagnosis of melanoma, Kaposi’s sarcoma and other tumors when the history of trauma and the physical examination are not consistent with a simple subungual hematoma.

References:

• Seaberg DC, Angelos WJ, Paris PM: Treatment of subungual hematomas with nail trephination: a prospective study. Am J Emerg Med 1991;9:209-210.
• Simon RR, Wolgin M: Subungual hematoma: association with occult laceration requiring repair. Am J Emerg Med 1987;5:302-304.

-----------------------------------------------------
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
-----------------------------------------------------