Subungual Hematoma

Updated 3/2017-- photos and all links removed as many are no longer active and it was easier than checking each one.

Subungual means "under the nail". Hematoma refers to a collection of blood. A subungual hematoma is blood under the nail. You will see a discoloration (red, maroon, or other dark color) under the nail. Keep in mind that not all dark patches under the nail are subungual hematomas. Consider the diagnosis of melanoma, Kaposi's sarcoma and other tumors when the history of trauma and the physical examination are not consistent with a simple subungual hematoma.

Subungual hematomas occur most often from a "crush-type" injury to the tip of the finger. These injuries include hitting your finger with a hammer, closing your finger in a door, etc. There is often intense pain when the injury occurs and later as the hematoma forms due to increased pressure that builds up between the nail and the very sensitive nailbed. Given time, the tissues surrounding this collection of blood will stretch and deform until the pressure within this collection of blood equilibrates. Within 24 hours the pain therefore subsides and, although the patient may continue to complain of pain with use of the finger/hand, performing a trephination (drilling a hole in the nail) at this time may not improve his discomfort to any significant extent and will expose the patient to the risk of infection. If you, the doctor, choose not to perform a trephination explain this to the patient who may be expecting to have his nail drained . There is some risk of missing a nail bed laceration under the hematoma, but, for most underlying lacerations, splinting by its own nail may be superior to suturing. When there are associated lacerations, open hemorrhage or broken nails, a digital block should probably be performed and the nail lifted up for inspection of the nailbed and repair of any lacerations. The pain may also be from other associated injuries such as a fracture to the underlying bone.

For you, the injured:

• If the pain is mild and the hematoma (blood collection) is less than 25% (one-fourth) of the area under the nail, then home care is recommended. This includes ice, elevation (keep your hand above your heart level), and anti-inflammatory medications such as ibuprofen.
• If the hematoma is 25% or more of the area and/or the pain is severe, then medical attention is recommended. Remember a fracture or laceration under the nail may have occured from the crush injury. An x-ray will need to be taken to access the possibility of a fracture.

For you, the doctor:

1. X-ray the finger to rule out an underlying fracture of the distal phalanx
2. Check for a possible avulsion of the extensor tendon (mallet finger).
3. Perform a trephination (clear instructions here) at the base of the nail, using the free end of a hot paper clip, electric cauterizing lance or drill. Tap rapidly with the cautery a few times in the same spot at the base of the hematoma until the hole is through the nail. When resistance from the nail gives way, stop. Further downward pressure may damage the nail bed.
4. Presistant bleeding from this opening can be controlled with a folded guaze held firmly over the "hole" by the patient and elevation of the hand.
5. Apply an antibacterial ointment, such as Betadine or Bacitracin, and cover the trephination with a Band-Aid.
6. Instruct the patient to keep his/her finger dry for 2-3 days and not to soak it for a week (no dish washing, no swimming). This is to prevent infection.
7. Inform the patient that he/she will eventually lose the fingernail. It will take 4-6 months to regrow.
8. If there is an underlying fracture, an aluminum finger tip splint may be aide in comfort and protection. The patient should keep the finger dry for 10 days (added increase risk of infection) and be given instructions to return at the first sign of infection.

Some precautions

1. Do not perform a trephination using a hot cautery device on a patient wearing artifical acrylic nails. These are flammable.
2. Do not perform a trephination when there is an underlying fracture, as this converts a closed fracture into an open one. If there is sufficient pain to justify the trephination, then the patient should understand the increased risk of infection.
3. There is no need to perform a trephination on a patient who is no longer experiencing any significant pain at rest.
4. Make sure the opening (trephination) is large enough for free drainage.
5. Do not send the patient home to soak his finger after a trephination. This will break down the protective clot and introduce bacteria.
6. There is no need to routinely prescribe antibiotics for this injury.
7. Do not remove an intact fingernail even with a large hematoma. it is not necessary to inspect the nailbed for lacerations or repair them with a closed injury.

References:
Subungual Hematoma by Craig Feied, MD, Mark Smith, MD, Jon Handler, MD, and Michael Gillam, MD; NCEMI

Comparison of Nail Bed Repair versus Nail Trephination for Subungual Hematomas in Children; Journ Hand Surg, 1999 Nov; 24 (6):1166-70; Roser SE, Gellman H

Fingertip Injuries--American Family Physician

Subungual Hematoma--eMedicineHealth article