Blood Under Your Nail (Subungual Hematoma)

How Physicians Treat Blood Under the Nail (Subungual Hematoma)

Toe Injury
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Your fingers and toes serve as the first contact with the world. Thus, your fingernails and toenails are especially prone to injury whether it be a stubbed toe or fingertip crushed by a power tool. Sometimes such injury results in a bleed under the nail, a condition called subungual hematoma. These bleeds can result in darkened discoloration (black nail), pressure and pain and can benefit from medical attention.

Subungual Hematoma Explained

With subungual hematoma, injury to the nail results in bleeding (hematoma) at the level of the nail bed (under the nail plate) or nail matrix. The nail matrix is a rapidly dividing layer of cells at the base of the nail lying toward the cuticle. Rapidly dividing cells of the nail matrix fill with keratin and thus become hardened nail. More extensive damage to the nail can not only result in bleeding under the nail (simple subungual hematoma) but also more extensive damage to the nail fold or digit itself.

If left untreated, a simple subungual hematoma typically grows out with the lengthening nail plate and resolves on its own. Until the nail grows out, however, you can expect weeks to months of blue-black discoloration (fingernails grow faster than toenails). 

In addition to discoloration, blood under the nail can result in pressure and pain, which can be relieved by a primary care physician or podiatrist ("foot doctor").

  With pain and severe injury secondary to subungual hematoma, you should also see a health care provider because there may be a toe or finger fracture.  Delayed treatment can result in nail deformity or infection. Of note, sometimes subungual hematomas can result in your nail falling off (onycholysis).

 

Subungual Hematoma: What Else Could It Be?

Based on the history and physical exam, most cases of subungual hematoma can be readily diagnosed (and treated) by your health care provider. When a fracture is expected, an x-ray is needed.

Rarely, what appears to be a subungual hematoma can be something else such as:

  • nail bed nevus (a mole or birthmark that grows slowly or not at all)
  • splinter hemorrhage (indicative of psoriasis or endocarditis)
  • longitudinal melanonychia (pigmented bands)
  • melanoma 

Of note, the above lesions are painless, and, unlike subungual hematomas, these lesions don't change or change slowly. Because some of these differential diagnoses are serious, like endocarditis (heart infection) or melanoma (skin cancer), it's a good idea to have your nails checked out by your physician when you notice something suspicious.

Treatment for Subungual Hematoma

It takes about 48 hours for blood at the level of the nail bed to clot. During this time, this blood can be drained by a physician, a process called nail trephination.

 

During nail trephination, a physician will use a hot metal wire, electrocautery device, or spinning, large-bore needle to pierce the nail bed. The hole created by piercing should be large enough to let the blood drain which takes about a day or two. During this time, the hole through which the blood extravasates or oozes should be covered with sterile gauze. 

After nail trephination, you won't need antibiotics although a pain reliever like ibuprofen may help with residual pain. After trephination, make sure to follow all your physician's instructions (including instructions to soak the affected area and apply clean dressing) and follow up with your physician as prescribed.  If it appears that the affected area reaccumulates blood or becomes infected, immediately contact your physician.

Fortunately, the nail bed lacks innervation so nail trephination doesn't hurt.

When the hematoma covers more than half the nail, your physician may choose to remove the nail completely. Moreover, if the nail injury is deep, the nail may also be removed, Before removing the nail, your physician will perform a digital block in order to anesthetize the area.

Selected Sources

Usatine RP, Smith MA, Chumley HS, Mayeaux EJ, Jr. Chapter 196. Subungual Hematoma. In: Usatine RP, Smith MA, Chumley HS, Mayeaux EJ, Jr.. eds. The Color Atlas of Family Medicine, 2e. New York, NY: McGraw-Hill; 2013. Accessed August 19, 2015.

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