Emergency physicians frequently deal with patients who have suffered trauma to their digits. This column begins a series on the clinical approach to common fingertip injuries that usually can be handled by the emergency physician by reviewing the treatment of subungual hematoma (SUH).
An SUH is a painful problem, often exquisitely so, that can bring the most hardy and stoic construction worker to the ED for immediate treatment. Even narcotics may fail to relieve the pain produced by an expanding subungual hematoma as it compresses the sensitive nail bed, and some method to release the pressure is usually required. There are few controlled studies in the literature that critically evaluate various therapeutic modalities, treatment recommendations vary greatly, and unsubstantiated clinical dogma about this entity is rampant. Probably the most common misconception is that simple injuries require aggressive treatment, such as removing the nail and repairing the nail bed.
Although it's not a major digit-threatening injury or rarely even an ultimate cosmetic concern, a subungual hematoma is usually totally treated by an EP or even a nurse practitioner/physician assistant, and all should be expert in the care of this injury. The key to a successful outcome of any fingertip injury is to know when to be conservative and when to be aggressive.
Most emergency medicine textbooks devote little time to the evaluation and treatment of SUH, and housestaff usually learn from on-the-job experience. Some continue to repeat the mistakes of equally misinformed mentors because even otherwise seasoned physicians may not be cognizant of the issues involved. Because we do not usually see the long-term result, ignorance is bliss. Mismanagement can lead to prolonged morbidity or even occasionally permanent deformity.
Treatment of Subungual Hematomas with Nail Trephination: A Prospective Study, Seaberg DC, et al, Am J Emerg Med, 1991;9(3):209
This nicely done prospective study was designed to determine if simple nail trephination alone would adequately treat uncomplicated SUH without producing or fostering associated cosmetic or infectious complications. This is the only study I could find that prospectively attempts to answer this rather common question. Over a period of two years, 48 patients who presented to the ED with SUH were entered into the study. Only simple SUHs were included.
Patients were excluded if they had disruption of the nail itself, if the nail was loose or the nail border was violated, or if previous nail deformities existed. Therefore, the study population included only patients with a closed hematoma, an intact nail, and no laceration of the external skin or disruption of the nail proper. Importantly, an underlying distal phalanx fracture did not exclude patients from the protocol.
Ages of the subjects ranged from 3 to 60. All patients underwent radiographic analysis, and were treated with electrocautery trephination and expression of the subungual blood. Antibiotics were apparently not prescribed.
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Figure: A number of devices are available to trephine a nail. A hot paperclip makes a small hole, but it's usually an effective drainage technique if a few holes are drilled. A butane lighter heats the clip, but a few attempts in the same hole may be necessary before the nail bed is reached. Twirling an 18-gauge needle requires a delicate touch that is not easily mastered. A consistently reliable method is to remove a generous square of nail with a cautery wire. A digital nerve block, while not always required, is suggested, and is appreciated by the patient when the device presses on, and then pops through, the nail.
Postoperative treatment included splinting of fractures in extension for one week. Patients were followed for at least six months after the injury for evaluation of deformities, dysfunction, or signs of infection.
Figure: The author prefers a large hot paperclip to make a single hole.
The size of the hematoma was rated relative to the nail surface area. The SUH involved more than 50 percent of the nail surface in more than half of the patients; 30 percent had an associated tuft fracture. Although most patients with underlying fractures had a greater than 50 percent hematoma, there was no close correlation between the size of the hematoma and the presence of a fracture.
There were no complications directly related to the trephination, and there were no cases of soft tissue infection, osteomyelitis, or permanent significant nail deformity. A few patients were noted initially to have ridges in the nail at the site of trauma; however, at three months these ridges had grown out and the nails appeared normal. It took an average of four months for a new nail to replace the old one following trephination. Importantly, these excellent results were achieved regardless of the size of the SUH or the presence of an underlying phalanx fracture.
The authors question the need for routine radiographs in all cases. They conclude that patients with uncomplicated SUH will obtain excellent results with simple nail trephination without removing the nail or suturing the nail bed. This conclusion is contrary to other authors, many of whom have suggested routine removal of a nail to repair all nail bed lacerations.
The authors emphasize that their study examined only cases where the nail and nail margins were completely intact, and their conclusions may not be applicable to extensive crush injuries or complex nail disruptions. They also state that the electrocautery device provides the most ideal method for rapid and painless trephination. If a fracture is present, routine protective extension splints were suggested. There appeared to be no role for routine antibiotic coverage, even if the phalanx was fractured.
Comment It is certainly undesirable for any patient to end up with a permanently deformed nail, especially if it's considered a minor injury. Many construction workers may not care, but a 15-year-old woman with an SUH of her ring finger has a right to be upset if her nail is permanently disfigured by physician mismanagement. It's clear, however, that some physicians are truly in a clinical fog when it comes to evaluating and treating such injuries. When I discussed this problem with some of my colleagues, I was amazed that their clinical approaches varied so widely. Erudite pontification was often accompanied by a lot of shoulder shrugging when the issues were further discussed. I also was amazed at the lack of specific knowledge by nascent housestaff.
Figure: This finger was slammed in a door, causing an acute flexion/crush injury. Often there is an avulsion of the extensor tendon (Mallet finger) but not in this case. On first glance the nail seems intact, an x-ray shows no fracture, and this could be mistaken for a simple 100% subungual hematoma. However, note the blood under the cuticle. How did it get there?
Figure: When the hematoma was evacuated and the loose skin debrided, the pathology became clear.
Figure: The only way for blood to accumulate under the eponychium (cuticle) is for the fingernail to be avulsed at the base, seen here lying free over the cuticle.
Figure: The nail is easily lifted off the nail bed and the nail bed laceration is repaired with absorbable suture. Never use sutures that have to be removed. A tourniquet is mandatory to see what you are doing.
Figure: The avulsed fingernail is then replaced under the cuticle and sutured in place. In two weeks, it can be removed as a new nail advances.
The majority of fingertip injuries can be handled in the ED, but it's paramount to pay close attention to detail. It is most important to put the natural evolution of the injury into proper prospective when deciding on therapy. Importantly, too much treatment can be as harmful as too little. This study provides convincing evidence that conservative treatment for uncomplicated SUH is ideal.
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[4]: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).
Figure: This 25% subungual hematoma, with the nail and nail edges intact, is easily drained with a hot cautery wire. There must be an injury of the nail bed, but do not remove the nail to suture the nail bed laceration. Even if there is an associated tuft fracture (perhaps technically it's an open fracture when the blood is drained), there are no data to support the use of antibiotics.
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.
Figure: The clinician made two mistakes here. Too small of a hole was drilled and the blood reaccumulated. Also, the doctor failed to recognize that the nail had been avulsed and was lying over the eponychium.
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[6]: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.
