Definition & Overview

The evacuation of subungual hematoma is a procedure used to treat bleeding underneath the nail. The procedure, also known as drainage or trephination, can remove the blood and other fluid that becomes retained under the nail due to the said condition. The procedure can effectively relieve the pressure and pain that normally accompanies the condition, while also minimising the risks and complications the patient may face during the treatment.

Who Should Undergo and Expected Results

Patients who should undergo an evacuation of a subungual hematoma are those who have blood and other fluid trapped under the nail. The blood and other fluid come from small blood vessels under the nail that has ruptured. This is, in most cases, caused by a traumatic injury to a finger or toe, but can also be caused by tight-fitting shoes.

A subungual hematoma is accompanied by the following symptoms:

  • Pain and pressure under the nail
  • Soreness and tenderness to touch
  • Discolouration of the nail, starting from red then changing into purple, dark brown, and black as the blood begins to clot

Most subungual hematomas can heal even with minimal treatment, such as applying ice to the injured area, elevating the finger or toe, and compression. The pain can also be managed with over-the-counter pain medications. However, in some cases, the patient may require treatment, namely the evacuation of the blood and other fluid trapped under the nail. Examples of situations wherein medical treatment may be necessary include:

  • Persistent pain (even when the finger or toe is at rest)
  • Severe pain
  • Worsening pain
  • Significant injury to the base of the nail

The severity of the injury is determined by performing the following tests on the injured finger or toe:

  • Extensor and flexor tendons testing
  • Capillary refill to test the circulation
  • Check the sensitivity of the affected area
  • X-rays, which help rule out a possible crush injury or distal phalanx fracture

An evacuation procedure as a treatment for subungual hematoma is effective in treating the condition by giving the trapped fluid an outlet to drain out of. This is done by penetrating the nail plate but without breaching the nail bed. The method is quick, convenient, and causes minimal risk and discomfort to the patient. After the procedure, the patient can expect an immediate relief from pain.

However, the procedure can only be performed if the edges of the nail are still intact despite the injury. For severe injuries that involve deep lacerations and disrupted nail edges, an evacuation is not the appropriate treatment. The procedure is also not appropriate for when the blood is already draining out by itself.

How is the Procedure Performed?

During the evacuation of a subungual hematoma, the patient is first given a nerve block to numb the affected area. In most cases, anaesthesia is not necessary. The fluid is then drained out by making a hole through the nail, which can be done through several methods. In the past, doctors have used heated needles or paper clips, but the most commonly used techniques now are drilling and hot cautery.

The procedure is performed by penetrating the nail at an angle depending on the location of the pooled blood under the nail. Even without applying pressure, the blood usually drains out within a minute. The procedure will continue until all the blood has been drained out. At the end of the procedure, the doctor may apply slight pressure to ensure total evacuation of the hematoma.

After the procedure, the doctor will clear any debris and any remaining blood using a sterile gauze pad and alcohol.

Possible Risks and Complications

The evacuation of a subungual hematoma is a relatively safe and simple procedure with minimal risks and complications. It is also not painful since there are no nerves in the nail plate, which is why some doctors do not administer a nerve block anymore. Patients are advised to seek medical attention rather than to attempt to drain the trapped fluid or remove the nail on their own, as an incorrect procedure may cause infection, additional trauma, lasting damage to the nail, and delayed healing.

While all these can be avoided through a professionally performed evacuation, there are still some potential risks, although they occur only rarely. These include:

  • Injury to the nail bed, especially if the nail penetration is too deep
  • Infection (if bacteria is accidentally or unknowingly introduced into the drainage site during the evacuation)

There is also a small risk of an unsuccessful evacuation, as not all cases of subungual hematoma can be treated through this method. This is more likely to occur if the injury is not promptly treated, as some hematomas may reach the matrix and thus cause secondary dystrophy. If this occurs, the hematoma may become too widespread and the evacuation procedure will be more complex.


  • “Subungual hematoma.” American Osteopathic College of Dermatology.

  • Chin-Ta Lin, Yuan-Sheng Tzeng. “How I Do It: Evacuation of subungual hematoma with an 18-gauge syringe needle.” Wounds: A compendium of clinical research and practice. 2014;26(2):E5-E6.

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