Your doctor may call it a “subungual hematoma” if you have bleeding under a fingernail or toenail. It usually happens if the nail gets crushed in an injury. It can cause symptoms such as intense pain and throbbing as blood collects under the nail.
Unless you also have broken bones or damage to the nail bed and/or surrounding tissues, this injury usually isn’t worrisome.
These injuries can happen easily. You might:
- Slam your finger in a car door or house door
- Hit your finger with a heavy object such as a hammer
- Drop a heavy object such as a dumbbell on your toe
- Stub your toe on a hard surface
If you have a darkened area under a nail and haven’t had an injury, see your doctor to rule out other possible causes.
The most common symptom is severe, throbbing pain. It happens because of the pressure of blood collecting between the nail and the nail bed.
You may also have:
- A dark-colored discoloration (red, maroon, or purple-black) under all or part of the affected nail
- Tenderness and swelling of the tip of the affected finger or toe
If you had a severe blow to a finger or toe, either seek immediate medical attention from your doctor or go to an emergency room. You should do this in case you have broken bones or serious damage to the nail bed and/or surrounding tissues.
Your doctor will examine your nail. You’ll probably also have an X-ray taken to see if you have a bone fracture or other injury.
A painless and small subungual hematoma usually doesn’t need treatment. But the pressure generated by pooled blood under the nail can be extremely painful.
To relieve the pain, your doctor may perform decompression, also called trephination, which allows the underlying blood to drain, relieving pressure and pain to the area.
Your doctor may numb the affected finger or toe with a nerve block and use one of the following decompression methods:
Cautery. The doctor uses a heated wire (electrocautery device) or carbon laser to burn a hole or holes. The heated tip of the wire is cooled by contact with the hematoma, which prevents injury to the nail bed. This is a quick and painless procedure.
Needle. The doctor uses a needle to make a hole in the nail.
After the procedure, your doctor will bandage your nail. You will need to keep the finger or toe bandaged and elevated -- and may also need to use cold compresses -- during the first 12 hours after decompression. In some cases, your doctor may recommend you use a splint for as long as 3 days until the tenderness subsides.
The main complication associated with decompression is a small risk of infection in the residual hematoma.
If you have bleeding under a large area of the nail surface, the nail bed may be injured. In this case, your doctor may need to remove the entire nail and use stitches to repair the nail bed.
Unless the area of bleeding is very small, an affected nail will usually fall off on its own after several weeks because the pooled blood has separated it from its bed.
A new fingernail can regrow in as little as 8 weeks. A new toenail may not fully regrow for about 6 months. If there has been injury to the nail bed and/or surrounding tissues, the new nail may take longer to grow.
Even with the best repair, there is still a possibility that the new nail may grow back and not look normal. See your doctor if you notice any problems with the nail as it heals and regrows.