A subungual hematoma is a collection of blood trapped beneath a fingernail or toenail, typically resulting from direct trauma. This injury can occur from incidents like stubbing a toe, hitting a finger with a hammer, or crushing the digit. While often painful due to pressure buildup, not all hematomas require medical drainage. Understanding the natural progression and potential outcomes when a subungual hematoma is left undrained is important.
The Body’s Response to Undrained Blood
When trauma causes blood vessels beneath the nail to rupture, blood pools in the confined space between the nail plate and nail bed. This accumulation creates significant pressure, leading to throbbing pain and tenderness. The intensity of this pain is directly related to the amount of blood trapped and the resulting pressure.
As time progresses, the body initiates its natural healing processes. The trapped blood begins to clot, and the initial pressure may gradually subside, leading to a reduction in pain over several days. The body then works to resorb components of the clotted blood. The blood beneath the nail dries and solidifies, forming a dark discoloration.
The nail remains intact, protecting the underlying nail bed. Minor subungual hematomas can resolve naturally without intervention. However, the hematoma can cause the nail to feel sore or tender to the touch, even after the most acute pain has diminished.
Potential Long-Term Nail Changes
Leaving a subungual hematoma undrained leads to visible changes in the nail over time. The pooling blood causes discoloration, appearing initially as red or purple, then gradually turning dark brown or black as it clots and dries. This discolored area will grow out with the nail.
As new nail grows from the nail matrix at the base, it pushes the discolored portion forward. This process takes several months; fingernails typically grow out in about six to nine months, while toenails may take longer, often 9 to 18 months. Pressure from the hematoma can sometimes cause the nail plate to separate from its bed, a condition known as onycholysis.
The affected nail may lift or detach completely as new nail grows underneath. Once the damaged portion of the nail reaches the free edge, it can be trimmed away, or it may shed naturally. If severe trauma damaged the nail matrix—the tissue responsible for nail growth—the new nail might grow back with a different shape, ridges, or other abnormalities, or in rare cases, not at all.
Signs That Medical Attention is Needed
While many subungual hematomas heal without medical intervention, certain signs indicate professional evaluation is necessary. Severe or worsening pain that does not subside after a few days, or intense throbbing pain covering a significant portion of the nail, warrants medical attention.
Signs of infection are a clear indicator for seeking medical care. These include increased redness, swelling, warmth, or tenderness around the nail. Pus draining from under the nail, red streaks extending from the injured area, or a fever are also strong signs of a developing infection.
A medical professional should also assess the injury if there is suspicion of an underlying bone fracture. This concern arises from severe impacts, such as dropping a heavy object on the digit, or if the finger or toe appears deformed. Additionally, if the hematoma covers a very large portion of the nail, generally more than 25% to 50% of the nail bed, or if bleeding does not stop, it should be evaluated to determine the extent of the damage to the nail bed and rule out other injuries.
Home Care and Observation
For subungual hematomas that do not require medical drainage, proper home care and vigilant observation are beneficial. Protecting the injured nail from further trauma is important, which can involve avoiding activities that might put pressure on it or wearing protective footwear if the toe is affected. Keeping the area clean helps prevent infections.
Applying ice to the affected area can help reduce swelling and discomfort in the initial stages. Elevating the injured hand or foot can also minimize swelling. Over-the-counter pain relievers can manage any lingering pain.
Monitor the hematoma for any changes, especially the warning signs that indicate a need for medical attention, such as increasing pain, signs of infection, or concerns about a fracture. Patience is required, as the discolored nail will gradually grow out over several months as new nail replaces it.