Subungual Hematoma
A subungual hematoma is a collection of blood trapped in the narrow space between the nail plate and the nail bed. It is one of the most common acute nail injuries seen in dermatology and trauma care.
The problem stems from the unusual anatomy of the nail bed:
- The nail bed has a dense, lengthwise network of capillaries, arteries and veins, squeezed between two rigid structures that cannot stretch: the distal phalanx below and the keratin nail plate above.
- A direct blow (a heavy object dropped on the digit, a finger caught in a door, a sports injury) or repeated microtrauma (long-distance running, sneakers that are tight at the toe) tears these nail bed vessels.
- The escaping blood is trapped in a closed space with no room to expand. The rising pressure presses directly on pain receptors (nociceptors), causing severe throbbing pain in time with the pulse, and it can distort the nail or lift it away from the nail bed (onycholysis).
When managing a subungual hematoma, the goal is not only to relieve the acute pain with sterile decompression but also to check for associated injuries such as a fracture of the distal phalanx or an extensive nail bed laceration. At Haute-Derma, we carefully assess the size of the hematoma, order an X-ray when a fracture is suspected, and clearly distinguish an acute traumatic bleed from a persistent pigmented lesion such as subungual melanoma.
Clinical Features and Severity Grading
Signs and Symptoms
- Pulsatile pain: Comes on quickly after the injury and worsens as pressure builds in the closed space under the nail.
- Color changes: The blood is bright red or red-purple at first, then after 24–48 hours turns dark red, purple, blue-black or brown-black as hemoglobin breaks down into hemosiderin.
- Outward migration: As the nail grows, a benign hematoma moves steadily toward the free edge, and healthy pink nail appears behind it near the cuticle.
Severity Grading
- Mild (less than 25% of the nail): A localized collection with little or no pain, no serious nail bed damage and an intact distal phalanx.
- Moderate (25%–50% of the nail): Considerable pressure with persistent aching; the nail plate starts to shift or lift slightly from the nail bed.
- Severe (more than 50% of the nail): Often accompanied by a complex nail bed laceration, nail matrix injury or distal phalanx fracture. Without repair of the nail bed, there is a high risk of permanent nail deformity (ridged, split or fan-shaped nails).
Subungual Hematoma vs. Nail Melanoma
| Feature | Subungual Hematoma | Subungual Melanoma |
|---|---|---|
| History of injury | Clear (crush injury, tight shoes, sports) | Usually no clear history |
| Pain | Severe, acute throbbing pain after injury | Usually painless in early stages |
| Border and shape | Rounded or irregular patch or collection | Longitudinal band with irregular, blurred borders, wider than 3 mm |
| Movement with nail growth | Moves outward with the nail plate | Stays in place, gradually widens and darkens |
| Hutchinson's sign | Negative (pigment confined to the nail plate) | Positive (pigment spreads onto the nail fold skin) |
| Onychoscopy | Red-purple to brown globules or clumps, no bands | Asymmetric, broken pigment pattern with loss of parallel lines |
Management, Surgical Treatment and Recovery at Haute-Derma
Conservative Management
- When: Small hematomas (under 25% of the nail) with little or no pain, a firmly attached nail plate and no suspected fracture.
- What to do: Apply cold packs for the first 24–48 hours (15–20 minutes at a time), keep the injured digit raised to reduce swelling, and take simple pain relief (acetaminophen/ibuprofen). The blood will grow out to the free edge over 2–6 months.
Nail Trephination (Decompression)
- When: An acute hematoma (within 24–48 hours) covering 25%–50% of the nail, with severe pain from pressure under the nail plate.
- Technique:
- Skin prep: The nail and nail folds are thoroughly cleaned with povidone-iodine or chlorhexidine.
- Decompression: A dedicated electrocautery tip or a large sterile needle (18G–21G) is gently rotated over the center of the hematoma to make 1–2 small holes through the nail plate.
- Drainage: The built-up pressure pushes the trapped blood out right away, relieving the pressure and the pain almost instantly.
- Dressing: A light sterile dressing is applied and changed daily, with antibiotic ointment to prevent secondary infection.
Nail Bed Repair Surgery
- When: A hematoma covering more than 50% of the nail, a torn or loose nail plate, or a displaced distal phalanx fracture on X-ray.
- Procedure: Under a digital block, the damaged nail plate is removed, the clot is cleared and each nail bed tear is carefully repaired with very fine absorbable sutures (6-0 or 7-0). The original nail plate (or sterile mesh gauze) is then replaced as a splint to keep the nail fold from scarring down.
