A bruised fingernail or toenail is usually the result of a direct hit to the nail, for example a concrete block dropped on the toe or a hammer slammed down on the thumbnail. When a toenail or fingernail receives direct, forceful trauma blood can gather between the nail bed and the finger or toe nail itself.
Some people refer to this incident as a blood blister under nails. However, the more accurate term is a subungual hematoma. Pooling blood under toenail or fingernails can be intensely painful because of the pressure that builds between the nail and nailbed.
A bruised fingernail that is left untreated can take a very long time to resolve. Most black toenails and black fingernail discoloration is the result of old blood under bruised nails.
The painful pressure and fingernail discoloration caused by blood building up under the nail can be relieved using a fairly simple procedure. Any primary care physician can do this in his or her office.
Before we get to the actual procedure, all individuals should be aware of contraindications to the technique used to release a blood blister under fingernails or toenails. These include:
-crushed or fractured nail bed
-bruising (hematomas) covering more than 50% of the nail. Blood under most of the nail may mean that the nail bed has sustained a cut and should be repaired in order to avoid fingernail deformities. Other physicians recommend leaving the nail in place so that it can act a splint for the damaged nail bed. Although in this case, fingernail deformities remain a possibility.
Procedure to remove blood blister under toenail, thumbnail or fingernail:
1. Gather the required equipment: Bunsen burner or alcohol lamp, metal paper clip, forceps or hemostat
2. Wash the affected finger or toe with an antibacterial soap. Wash the digit thoroughly in order to decrease the likelihood of infection.
3. Use the paperclip to make a small hole in the nail. This is done by partially straightening the paperclip. The part of the paperclip that wasn't straightened is then grasped with the forceps or hemostats. Heat the paperclip in the flame. Then place the heated paperclip firmly against the bruised nail until the hole goes completely through the nail. The ideal hole size is 1 to 2 mm.
For the next 12 hours, the finger or toe requires a bit of special attention. After the blood is released from beneath the bruised fingernail or toenail, the nail should be elevated. A bandaid or small piece of gauze can be placed over the hole in the nail. Cool compresses can then be used against the nail to help relieve any discomfort.
Source: Fowler, G., Pfenninger, J. Procedures for Primary Care. 2nd Ed. Mosby Inc. 2003.