A subungual hematoma is the medical term for blood trapped underneath a fingernail or toenail, typically appearing as a dark purple, red, or black bruise. This condition frequently results from blunt force trauma, such as crushing a finger in a door or dropping a heavy object onto a toe, which causes blood vessels in the sensitive nail bed to rupture. The pooling blood creates significant pressure against the nail plate, leading to intense, throbbing pain. The procedure to release this pressure is called trephination, which involves making a small hole in the nail to allow the trapped blood to drain, thereby providing immediate pain relief.
Recognizing When Not to Attempt Home Drainage
Draining a subungual hematoma at home is only appropriate for simple injuries. Professional medical attention is necessary if there are signs of a possible bone fracture, such as visible deformity, inability to move the affected joint, or pain extending significantly beyond the nail area.
If the injury involves a deep cut to the skin around the nail or a laceration of the nail bed, the wound may require stitches and should not be managed at home. A medical evaluation is also warranted if the hematoma covers more than 50% of the nail’s surface area or if the injury resulted from a severe crushing mechanism that affected the joint.
Existing signs of infection, such as pus draining, red streaking up the limb, or a fever, disqualify the injury for home treatment. Trephination should only be performed on hematomas less than 48 hours old, as older, clotted blood will not drain effectively.
Essential Preparation Steps Before Draining
Before attempting to relieve the pressure, gather the necessary materials to ensure a sterile and effective process.
Materials Needed
- A chosen tool for penetration (straightened metal paperclip or large-gauge needle).
- An antiseptic solution (povidone-iodine or chlorhexidine).
- Sterile gauze.
- A topical antibiotic ointment.
The affected finger or toe must be thoroughly cleaned first by washing it with soap and warm water, followed by applying the antiseptic solution directly to the nail surface. The penetration tool must be sterilized immediately before use to minimize the risk of introducing bacteria.
If using a metal paperclip, hold the tip with pliers and heat it in a flame until it glows red, achieving sterilization through cauterization. This method melts through the nail plate. If using a large needle or small drill bit, sterilize it with rubbing alcohol. Taking an over-the-counter pain reliever beforehand may help manage discomfort, though drainage often provides instant relief.
The Procedure for Relieving Pressure
The goal is to create a small hole in the nail plate directly over the pool of blood without touching the sensitive nail bed. Place the hole over the darkest, most raised area of the hematoma. Stabilize the finger or toe firmly on a flat surface.
If using the heated paperclip, gently touch the red-hot tip onto the nail surface at a 90-degree angle, allowing the heat to melt a path through the nail. Avoid applying downward pressure, which could cause the tool to plunge into the nail bed once penetration occurs.
If using a sterile needle or drill bit, apply gentle, rotational pressure, twisting the tool to bore through the nail plate. As soon as blood begins to seep out, the procedure is complete, and the tool must be immediately withdrawn.
The release of pressurized blood provides a near-instant reduction in throbbing pain. If drainage stops prematurely, gently enlarge the hole or create a second small hole nearby to ensure maximum decompression.
Immediate Aftercare and Monitoring
After drainage, gently squeeze the sides of the injured finger to encourage residual blood to exit the hole, ensuring complete pressure relief. Clean the wound site again using the antiseptic solution to remove blood and minimize infection risk. Do not soak the finger, as prolonged water exposure increases bacterial contamination risk.
Apply a topical antibiotic ointment directly over the trephination site. Cover the hole with a sterile bandage or gauze to protect it from dirt. Change the dressing daily, or whenever it becomes wet or soiled, applying fresh antibiotic ointment each time to maintain a clean environment for healing.
Monitoring for Complications
Monitor the injury closely for signs of complication in the days following drainage. Seek medical attention if you notice increasing redness, swelling, warmth, or a foul odor around the nail, or if pus begins to drain. A persistent or worsening fever also indicates a systemic infection requiring professional care.
The discolored nail will gradually grow out over several months. While the entire nail may eventually separate from the nail bed, a new, healthy nail will replace it, provided the underlying matrix was not severely damaged.