The traumatic accumulation of blood beneath the nail plate can create an excruciatingly painful injury. The often pulsatile pain is caused by increased pressure from the blood within a closed space adjacent to the sensitive nail bed and matrix. Subungual hematomas frequently manifest with a blue-black discoloration that can extend beneath part or all of the nail surface. The pain of a subungual hematoma can be dramatically and instantaneously relieved after evacuation.
Trephination provides a simple technique to evacuate hematomas. Various techniques have been advocated, including the use of heated paper clips, scalpel blades, dental burrs, and cautery units. Because the nail plate has no sensation, anesthesia generally is not required. Care should be exerted with any trephination instrument, because downward pressure increases pain. The use of a hot-tipped cautery unit is advocated because it burns a hole through nail plate without the need for much downward pressure or mining. The examiner must be prepared to lift up immediately on passage through the nail plate to avoid injury to the sensitive nail bed.
Over time, the tissues surrounding the hematoma stretch, and the pain subsides. There appears to be little pain relief obtained from draining a hematoma after about 48 to 72 hours following the initial injury. The discoloration of a subungual hematoma will grow out with the nail and be replaced with normal-appearing tissues.
Up to 25% of all subungual hematomas are associated with a fracture of the distal phalanx. The size of the subungual hematoma does not correlate with the presence of a fracture, and some physicians advocate routine x-ray examination. If fracture is identified, 60% of those nails have a laceration large enough to warrant closure with a small, absorbable suture. The major incentive to nail bed exploration and laceration repair is to prevent permanent nail dystrophy or deformity from a step-off or separated laceration.
Appropriate management of a subungual hematoma seeks to provide pain relief, recognizes associated injuries, and promotes regrowth of a functionally normal and cosmetically acceptable nail. Historically, it was recommended that hematomas involving more than 25% to 50% of the nail surface be explored. Nail plate removal and nail bed exploration was advocated to optimize the cosmetic outcome. The routine practice of nail bed exploration has been questioned by several
studies; it appears that the practice is justified only when a laceration is through the nail plate or through either of the lateral nail folds. If no laceration is detected, it is probably safe to evacuate the hematoma, although 1 in 12 still may experience residual nail change.
Evacuation of the hematoma. Hold the fine-tipped cautery vertically over the center of the hematoma (Figure 1A). Activate the cautery, and burn through the nail plate. As the nail plate is traversed, blood may spurt upward as the pressure is released (Figure 1B). As soon as the subungual space is entered, the operator must be prepared to pull up and not allow the hot tip to touch down on the highly sensitive nail bed (Figure 1C).
(1) Holding a fine-tipped cautery vertically over the center of the hematoma, burn through the nail plate until the subungual space is reached.
Alternately, a heated paper clip can also accomplish the evacuation. The metal paper clip is straightened and grasped with a hemostat for heating and nail plate drilling.
(2) Use of a heated paper clip for evacuation.
PITFALL: Avoid heating coated paper clips, which can produce a malodorous plume and burns from the molten coating. Avoid copper paper clips, which can melt.
If the nail is torn or if there is a laceration through the lateral nail fold, the nail plate can be removed and the nail bed explored (Figure 3A). Often, the nail matrix remains attached, whereas the distal nail may be separated from the nail bed. The distal nail can be cut free, and the laceration in the nail bed repaired with a fine (6-0) absorbable (polyglycan, Vicryl) suture.
(3) If the nail is torn or if there is a laceration through the lateral nail fold, the nail plate can be removed and the nail bed explored.
When evacuation of a hematoma is performed, only code 11740 usually is reported.
INSTRUMENT AND MATERIALS ORDERING
Fine-tipped battery cautery units are available from Aaron Medical (high-temperature cautery AA01, order athttp://www.hospitalnetwork.com) or from Advanced Meditech International (phone: 800-635-2452; thermal cautery CH-HI, about $35 each, order at http://www.ameditech.com). A suggested anesthesia tray that can be used for this procedure is listed in Appendix G.
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