Subungual hematoma
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A subungual hematoma is an accumulation of blood between the nail plate and the nail bed, most commonly resulting from trauma to a digit or repetitive pressure. Extravasated blood forms a red, bluish, brown, or black spot under the nail. In an acute injury, the increase in pressure under the rigid plate can cause intense, throbbing pain. Most small hematomas gradually migrate toward the free edge as the nail grows. Extensive lesions may coexist with nail bed damage, nail plate separation, or a fracture of the distal phalanx. Discolorations arising without an identifiable trauma, persisting in one place, or extending to the skin surrounding the nail require particular evaluation, as pigmentary disorders and neoplasms of the nail apparatus can produce a similar appearance.
Subungual hematoma - where does it come from
The direct cause of a hematoma is the rupture of small blood vessels in the nail bed or nail matrix. Blood accumulates under the plate, whose compact structure limits the expansion of tissues. This mechanism is responsible for the characteristic throbbing pain.
The most common mechanisms of hematoma formation include:
- crush injury, for example slamming a finger in a door or dropping a heavy object;
- direct blow to a finger or toe;
- repetitive microtrauma, typical of running, trekking, racquet sports, and team sports;
- pressure in footwear, especially when the toes slide forward while descending a slope;
- excessively long nail plate, which strikes against the front of the shoe;
- procedures performed within the nail area, especially aggressive treatment of the plate or nail folds.
The formation of hematomas can be favored by coagulation disorders, thrombocytopenia, and taking anticoagulant or antiplatelet medications. In such cases, even minor trauma can cause extensive extravasation.
A hematoma after a single trauma usually affects a single nail. Lesions on multiple toes more often indicate repetitive mechanical pressure. The diagnosis also takes into account splinter hemorrhages, onychomycosis, psoriasis, melanocytic nevi, and melanoma of the nail apparatus.
Subungual hematoma - what it looks like
The appearance of a hematoma depends on the time that has elapsed since the injury, the amount of extravasated blood, and the depth of the damage. A fresh lesion may be bright red or purple. As hemoglobin breaks down, it takes on shades of burgundy, navy blue, brown, and then brownish-black. The lesion may be homogenous, patchy, globular, or composed of short streaks.
A typical hematoma:
- appears after an injury or a period of intense stress on the digit;
- has a relatively distinct border on the matrix side;
- may occupy a part or most of the nail surface;
- moves toward the free edge as the nail plate grows;
- in the acute phase, causes tenderness, a feeling of pressure, and throbbing;
- sometimes coexists with swelling, skin abrasion, or partial onycholysis, which is the separation of the nail plate from the nail bed.
Dermoscopic evaluation of a hematoma often reveals homogenous areas, globules, streaks, and a gradual fading of color at the periphery. The most important feature observed over time is the distal migration of the lesion along with the nail plate.
Melanoma of the nail apparatus more often forms a longitudinal, irregular band of varying color and width. Alarming features include widening of the band toward the matrix, nail plate destruction, ulceration, a nodule, and pigmentation of the nail fold. The color of the lesion itself is an auxiliary criterion, as both a hematoma and a melanocytic lesion can appear brown or black. The medical history, dermoscopy, photographic documentation, and the dynamics of the clinical picture are of decisive importance.
Subungual hematoma - will the nail fall off
Loss of the nail plate depends primarily on the extent of the injury to the matrix and nail bed, the degree of nail detachment, and the coexistence of a fracture. A small hematoma with a stable, properly seated nail plate usually heals without losing it. The discoloration then gradually moves toward the free edge and disappears as the nail is trimmed.
An extensive injury can lead to onycholysis or the temporary cessation of nail plate production. A new nail begins to grow beneath the damaged portion, which gradually loses its connection to the nail bed and detaches spontaneously. This process may involve only a fragment of the plate or its entire surface.
The rate of regrowth depends on the location:
- fingernails usually require about four to six months for complete replacement;
- toenails grow more slowly, and complete regrowth can take from twelve to eighteen months;
- vascular diseases, diabetes, age, malnutrition, and further trauma can additionally slow down growth.
A properly preserved matrix usually produces a plate of correct structure. Deep damage to the matrix can leave a longitudinal groove, split, thickening, or permanent deformity. The damaged plate acts as a biological dressing, which is why tearing it off on one's own increases the risk of injury to the nail bed. A protruding, completely loose fragment can be safely treated by a doctor or podiatrist after prior tissue assessment.
Subungual hematoma - what not to do
A fresh injury requires protecting the toe, reducing pressure, and observation. During the first 24 hours, short periods of cooling through a cloth, elevating the limb, and covering the injured site with a sterile dressing can be helpful. Footwear should provide adequate space for the toes and stabilize the foot.
Risky actions include:
- drilling or burning through the nail yourself with a needle, pin, drill bit, or heated object;
- incising the skin and nail bed, which can lead to infection and scarring;
- tearing off the nail plate, even if it has become partially loose;
- squeezing blood out through the nail folds;
- applying nail polish, hybrid, gel, or reconstruction material to a fresh injury;
- continuing training or wearing tight footwear despite pain;
- aggressive milling of the discolored plate before establishing a diagnosis;
- masking the dark lesion without photographic documentation and monitoring its movement.
Particular caution should be exercised by people with diabetes, neuropathy, limb ischemia, reduced immunity, or bleeding disorders. Even a minor injury may require professional evaluation in their case. Care should focus on maintaining cleanliness, protecting against further pressure, and preserving a dry, safe environment around the nail.
Subungual hematoma - when does it require intervention
Urgent medical consultation is indicated in cases of severe throbbing pain, extensive hematoma, a crushed finger or toe, deformity, sensory impairment, restricted movement, heavy bleeding, or a suspected fracture. Medical attention is also required for a contaminated wound, damage to the nail folds, partial avulsion of the nail plate, and symptoms of infection: increasing redness, warmth, swelling, purulent discharge, fever, or worsening pain.
In the case of an acute, painful hematoma, a doctor may perform nail trephination, which is a small hole made in the plate to allow blood to drain and reduce pressure. The greatest benefit is usually achieved within the first several dozen hours after the injury. The size of the hematoma is only one of the qualification factors. Pain, stability of the nail plate, the condition of the nail folds, and the presence of a fracture are more significant. Removal of the plate and surgical management of the nail bed are considered in the event of its detachment, significant tissue damage, an extensive wound, or a fracture requiring stabilization.
A brown or black lesion requires a dermatological consultation when:
- it appeared without an identifiable injury;
- it remains in the same location despite nail growth;
- it forms an irregular, widening band;
- pigment spreads onto the skin of the nail fold;
- ulceration, a nodule, bleeding, or progressive dystrophy of the nail plate occurs.
At Ambasada Urody Clinic & SPA, podiatric procedures useful in the aftercare phase following an injury are available: podiatric consultation, onycholysis therapy, debridement of a diseased nail, basic or extended podiatric treatment, and nail reconstruction. Onycholysis therapy includes the safe preparation of the detached part of the plate, as well as cleaning and protecting the nail bed. Reconstruction can be considered after the tissues have healed, infection has been ruled out, and normal nail growth has been confirmed. An acute, painful hematoma, a fracture, and a suspected neoplasm require medical diagnosis first.
