What is a subungual hematoma?

Subungual Hematoma: Definition, Diagnosis, and Management

A subungual hematoma is a collection of blood underneath the nail plate that typically occurs following trauma to the finger or toe. It commonly results from crush injuries such as shutting a finger in a door or from repetitive trauma in athletes like runners and dancers 1.

Clinical Presentation

• Appearance: Blood accumulates between the nail plate and nail bed, creating a visible discoloration that may appear black, red, or purple
• Symptoms: Often accompanied by pain and pressure due to blood collection in the confined space
• Distribution: Can affect fingernails or toenails, with varying sizes depending on the extent of trauma

Diagnosis

Diagnosis is primarily clinical and based on:

• Recent history of trauma to the digit
• Characteristic appearance of blood collection under the nail
• Pain and tenderness of the affected digit
• Possible nail deformity if severe

It's important to distinguish subungual hematoma from:

• Subungual melanoma (which typically has irregular borders and pigmentation)
• Fungal infections (which usually present with nail thickening and discoloration)
• Bacterial infections (which often present with surrounding erythema and purulent discharge)

Management

Treatment depends on the size of the hematoma and associated symptoms:

Small, Asymptomatic Hematomas

• Conservative management with observation
• Pain control with over-the-counter analgesics
• Allow natural resolution over time as the nail grows out

Symptomatic or Large Hematomas

1. Nail Trephination (first-line treatment):

   • Creating a small hole in the nail plate to release trapped blood
   • Methods include:
     • Electrocautery device (most common in clinical settings) 2
     • Extra-fine 29-gauge insulin syringe needle (particularly useful for smaller hematomas of the second, third, and fourth toenails) 3
     • Heated paperclip or specialized trephination device

2. Post-procedure care:

   • Keep the area clean and dry
   • Apply topical antiseptic to prevent infection
   • Monitor for signs of infection or recurrent bleeding

Severe Cases

• In cases with significant nail bed injury or associated fractures, referral to a specialist may be necessary
• Nail removal is rarely required for simple subungual hematomas, regardless of size 2

Prognosis and Follow-up

• Most subungual hematomas resolve without complications
• The affected nail typically grows out in approximately 4 months (±2.6 months) 2
• No significant complications such as infection, osteomyelitis, or major nail deformities typically occur with proper treatment 2

Special Considerations

• Patients with hemophilia: May require factor replacement before any surgical intervention and are at higher risk of recurrent bleeding 4
• Diabetic patients: Subungual hemorrhage may indicate severity of diabetic microangiopathy 5
• Chronic or recurrent subungual hematomas: May warrant further investigation to rule out underlying systemic conditions

Proper treatment of subungual hematomas provides pain relief and prevents potential complications such as nail deformity or infection. Most cases have excellent outcomes with appropriate management.