The EP should approach SUH with this philosophy, and simply trephine the nail and discharge the patient, but it's easy to get sidetracked with aggressive nail removal and fancy nail bed repairs after a cursory reading of the hand surgery literature. Few emergency medicine texts devote a detailed discussion to this common problem, and because hand surgeons rarely see these minor injuries except when there are complications, the entire medical literature is sketchy. Reading the hand surgery literature would make even the most self-assured EP quickly opt for referral.
One of the most lucid and detailed discussions of fingernail injuries can be found in a 25-year-old article by Ashbell (J Trauma 1967;7:177) and a 10-year-old article by Rosenthal (Orthop Clin North Am 1983;14:675). These are a bit dated in their approach to some fingertip injuries, but the discussions about nail and nail bed injuries should be required reading for all EPs.
Impressively, and despite much clinical paranoia and unreferenced warnings in the literature about SUH, there were no signs of permanent nail deformities in any patient in this study. Only 48 patients were studied, but because my waiting room is not filled with fingers permanently deformed by this everyday injury, I am convinced that the authors' conclusions are valid. The lack of infectious complications, particularly in those patients with underlying fractures, also is comforting.
Although some physicians routinely prescribe antibiotics following trephination when there is a tuft fracture based on the theory that such injuries are actually compound fractures once drainage is performed, there are absolutely no data to support this protocol. I was surprised that so many of my colleagues steadfastly held to the routine antibiotic regimen. I believe one is on firm ground by withholding antibiotics post-trephination of an uncomplicated SUH, even with an underlying fracture. I personally never have seen or heard of osteomyelitis in such cases, but it's certainly possible. In a related but not identical scenario, there are numerous studies supporting no antibiotic coverage for other types of fingertip injuries, even those with partial amputations, exposed bone, or open tuft fractures (Ann Emerg Med 1983;12:358).
Importantly, I would likely use three to five days of post-trephination antibiotics (anti-staph/strep, such as cephalophin/Keflex) in the presence of an underlying fracture in immunocompromised patients (HIV, diabetes, long-term steroid users) or those with peripheral vascular disease, but certainly routine antibiotics are overkill. Tetanus toxoid is theoretically a good idea, but I could find no cases of tetanus from nail trephination. Trephination without tuft fracture in any patient does not cry out for antibiotics.
In a related study, Simon and Wolgin (Am J Emerg Med 1987;5:302) evaluated 47 adult patients with SUH to determine the association between the hematoma, associated fractures, and the presence of occult lacerations of the nail bed. The fingernail was removed to check for the presence of a “repairable laceration” in patients with an SUH greater than one-fourth of the nail bed.
They discovered that 60 percent of patients with an SUH greater than half the nail had a “laceration requiring repair.” The incidence of repairable laceration rose to 95 percent when there was an associated fracture. Patients were not followed for cosmetic results, and the authors did not define “repairable.” Of course, every SUH is accompanied by a nail bed laceration — that's how the blood got there in the first place. Maybe if you can see the laceration, it's “repairable.”
These authors, however, suggest that fingernails should be routinely removed, the nail bed explored, and lacerations sutured if the SUH is greater than half of the nail surface or if there is a phalanx fracture. In my opinion, this aggressive stance is not substantiated by their own data, and is overtreatment for a minor injury that will heal nicely with a more conservative approach. Once removed, it may take four to five months (1 mm per week) for a new nail to grow back. This is a long time to go without one's fingernail!
The nail bed certainly must be lacerated if an SUH is present, and the hematoma is the consequence of any physical disruption to a highly vascularized tissue. The contention that all nail bed lacerations must be meticulously approximated to avoid future nail cosmetic abnormalities is absurd. I believe this recommendation is clearly disproven by the Seaberg et al study. The intact nail is an ideal splint that provides integrity to the nail bed matrix and ensures close approximation of any laceration.
One need only try to remove a nail to be convinced that the nail is normally firmly attached to the nail bed. Removing the nail will certainly cause more trauma, and will likely make a minor rent in the bed look huge. Stabilization by the adherent nail is probably as good as can be accomplished with suturing the nail bed. If the nail remains attached at its margins, leave it alone.
Significant crush injuries, those that involve deep lacerations of the nail itself or the nail margin, or injuries that avulse the nail are completely different cases that should be approached in a different manner. In cases where a nail bed laceration extends to the skin or the nail is split, disrupted, or avulsed, it is generally agreed that the nail should be completely removed and the nail bed inspected and carefully repaired.
It is difficult to talk patients out of a routine x-ray for minor crush injuries of the fingernail. I would order x-rays if specifically requested by the patient, if there were gross deformity, or if it were important to predict accurately how long the pain would persist. Usually a fracture can be ruled out if there is no tenderness when longitudinally compressing the fingertip or carefully palpating the distal fat pad. Displaced phalanx fractures should always be reduced, but with a minor SUH and an otherwise normal appearing fingertip, I generally try to avoid x-rays (a tact often thwarted by the housestaff or triage nurse).
The presence or absence of an underlying crack in the distal phalanx is of no importance to initial therapy. Laborers, typists, or musicians may require an x-ray because fractures may mandate light duty or time off from work because of pain. A documented fracture may mean the difference between a few days and a few weeks of disability compensation. If my patient were a concert violinist, however, I must admit that I would refer to a hand surgeon if there were a tuft fracture.
Although no one disagrees that an SUH requires trephination, there is a wide variety of personal preferences for the trephination device and many variations on the actual procedure. Some patients can tough out a gentle trephination without anesthesia, but I find it more desirable and easier to obtain proper drainage with local anesthesia. I routinely perform a digital block with long-acting bupivacaine prior to nail trephination. I'll agree that the procedure can be done relatively painlessly if one gently uses the electrocautery, being careful not to exert downward pressure on the nail bed. If the cautery device is used, a large hole (3–4 mm) or multiple drainage holes should be placed. A single small hole may clot, and the hematoma can form again. The cautery is theoretically a single-use device, making this an expensive procedure.
I usually opt for the large paper clip (cheap and disposable) and butane lighter approach. Some physicians avoid this technique because it requires some painful pressure and because carbon particles may be deposited (unsightly yet benign). Be sure to hold the heated paper clip with a hemostat. Two or three tries in the same hole are usually needed before the nail is punctured, Blood usually spurts out under pressure and then slowly drains over the next few days. Gentle pressure will initially squeeze out most of the remaining blood (it rarely clots), and the patient can soak the finger in cool salt water for a few days.
It's a good idea to advise patients that the original nail may fall off if there was significant blunt trauma, but this is unusual or obvious at the time of injury. Subungual blood usually does not clot even after a few days, but one argument made to drain even small blood collections is that slow bleeding can continue and delaying evacuation may promote clotting.
Many SUHs are produced from injuries that cause excessive flexion to the distal phalanx. Therefore, one should always check for avulsion of the extensor tendon (mallet finger). In the excitement of draining the hematoma, this injury may be missed and produce a noticeable cosmetic deformity if treatment is not initially correct. Some authors advise prepping the nail with alcohol before cautery. I don't usually do this, but if it's done, be certain that the alcohol is dry because it will catch on fire with the cautery (and produce a nearly invisible flame).
Lastly, some unusual entities can masquerade as a subungual hematoma so don't assume that all dark patches under a nail are blood collections. Such things as malignant melanomas, Kaposi's sarcoma, pigmented nevi, glomus tumors, and splinter hemorrhages from endocarditis could cause some embarrassment if they were inadvertently assumed to be a simple SUH.
With specific regard to children and SUH, Roser and Gellman (J Hand Surg [Am] 1999;24:1166) found no difference in final outcome in 52 children randomized to simple trephination versus nail removal/nail bed repair in a two-year follow-up study. Again, the criteria for simple trephination was simply an intact nail and intact nail margin, regardless of the presence of an underlying tuft fracture. As expected, the cost of nail removal was at least four times that of simply placing a hole in the nail bed to drain the blood.
It seems logical to provide simple nail trephination in all patients with SUH, with ordering routine x-rays dictated by the individual situation. Adequate holes should be made in the nail to ensure continual drainage. Routine antibiotic coverage is unnecessary, even if there is a tuft fracture. If the nail is loose, split, or the laceration extends past the nail margin, the nail should be removed, the laceration of the nail bed repaired, and the nail reapplied as a dressing. Obviously all displaced fractures should be reduced and splinted as appropriate.
© 2003 Lippincott Williams & Wilkins, Inc.