What is a Subungual Hematoma?
A Subungual Hematoma is the medical term for a collection of blood trapped underneath the nail plate. It presents as a dark red, purple, or black spot that can cover a small portion or the entire surface of the nail bed. Because the hard nail plate cannot expand, the pooling blood creates intense pressure against the sensitive nerves below.
Two Types of Trauma
Hematomas are always caused by physical trauma to the toe, but the nature of the trauma dictates the symptoms.
Acute Trauma (Crush Injury)
- Cause: Dropping a heavy object on the toe or violently stubbing it.
- Symptom: Immediate, excruciating, throbbing pain due to rapid blood pooling.
- Action: Often requires urgent medical drainage (trephination) to relieve pressure.
Micro-Trauma ("Runner's Toe")
- Cause: The toe repeatedly jamming into the front of a shoe over thousands of steps (running, hiking).
- Symptom: Often painless or mildly tender. Discovered only when taking off socks.
- Action: Rarely requires drainage; needs better fitting footwear.
Will I Lose My Toenail?
It depends on the severity. If the blood pool covers less than 25% of the nail, the nail will usually stay attached, and the dark spot will slowly grow out over the next 9-12 months. If the hematoma covers more than 50% of the nail bed, the pressure has likely severed the attachment between the nail and the bed. The nail is effectively "dead" and will eventually fall off (Onychomadesis) as a new one grows underneath.
Clinical Treatment: Trephination
If you experience an acute crush injury and the throbbing pain is unbearable, seek podiatric care immediately. A podiatrist can perform a simple, painless procedure called trephination. A specialized heated wire or micro-drill is used to melt a tiny hole through the hard nail plate directly over the blood pool. This instantly releases the trapped blood and relieves the pressure and pain entirely. Do not attempt this at home with a hot needle, as it carries a massive risk of severe bone infection.