Have you ever been cooking in the kitchen and dropped a can of vegetables on your toenail ? Have you ever ran for a long time and developed blood under a toenail. I am guessing at some point you have had blood under the nail plate whether due to direct trauma or repetitive microtrauma. The scientific name for blood under the nail plate is subungual hematoma.
Subungual hemoatomas develop because the arteries in the nailbed (the tissue between the nail plate and the bone) get damaged. There is a potential dead space or vacant space that can form between the nail plate and the nail bed, which can fill with blood.
The pressure from the blood under the nail can cause severe pain.
Most patients present with with a swollen toe and complaints of throbbing pain following injury. The 2 most common mechanisms are repetitive microtrauma from sports such as running or tennis or direct trauma from a crush-type injury.
When looking at the nail plate, if the blood takes up more than 25% of the nail plate, then a fracture of the bone underneath usually occurs.
Treatment involves draining of the blood to relieve the pressure. Hematomas involving less than 25% of the nail plate are usually drained by poking a hole through the nail plate with a heated paperclip, a needle, or a hand-held cautery tool. Once the nail plate is penetrated, the blood under the nail is expressed using slight pressure. The area should then be cleansed a dressed with a sterile dressing.
When the blood collection involves more than 25% of the nail plate, there is increased risk of nail bed laceration. Therefore, complete removal of the nail is required in order to properly evaluate the entire nailbed.
Decompression of a subungual hematoma is quick, easy and painless. Patients feel immediate relief and generally have no complications following prompt drainage. Usually the nail will come off on its own in approximately 6 weeks after the trauma, and a new nail is regrown by 6-9 months without being disfigured.