Nail Trephination for Subungual Hematoma
Perform nail trephination immediately for any painful subungual hematoma, regardless of size, to provide symptomatic relief—this is the only intervention needed in most cases.
When to Perform Trephination
Trephination should be done when:
- Pain is present from the subungual hematoma (the primary indication)
- The nail and nail margins remain intact
- The patient presents acutely (ideally within 24-48 hours of injury, though delayed presentation up to 72 hours still benefits from drainage)
The size of the hematoma does not matter. The traditional "25% or 50% rule" has been debunked—studies show excellent outcomes with simple trephination regardless of whether the hematoma covers 10% or 90% of the nail bed 1, 2, 3.
Key Evidence Supporting Conservative Management
Multiple prospective studies demonstrate that simple trephination alone achieves excellent results in 85% of patients, with only 2% experiencing poor outcomes 3. A landmark study of 48 patients followed for an average of 10 months found zero cases of infection, osteomyelitis, or major nail deformities after trephination alone 2.
Most importantly, there is no difference in cosmetic outcome between nail bed repair and simple trephination, even when comparing large hematomas or those with underlying fractures 1. The operative approach costs approximately 4 times more ($1,263 vs $283) without providing superior results 1.
Technique
Use electrocautery or an 18-gauge needle to create a hole through the nail plate directly over the hematoma 2, 4. Patients report immediate pain relief following drainage 2, 5.
What NOT to Do
Do not remove the nail for exploration and nail bed repair unless:
- The nail margin is disrupted or avulsed
- A subungual abscess is suspected (not just hematoma)
- The nail is already detached
The presence of a distal phalanx fracture is NOT an indication for nail removal—studies show no difference in outcomes between fractured and non-fractured digits treated with trephination alone 2, 3.
Special Populations
In hemophilia patients, trephination should still be performed as standard of care, but only after appropriate factor replacement 6. These patients may experience recurrent bleeding in the first 2 weeks and require close follow-up with hematology 6.
Expected Outcomes
- Average time for new nail growth: 4 months 2
- Transient abnormalities (mild depression or hypertrophy) may occur but typically resolve by 4 months 1
- No long-term complications in the vast majority of cases 7, 1, 2, 3
Common Pitfall to Avoid
The most common error is over-treating these injuries with unnecessary nail removal and formal nail bed exploration based on outdated criteria about hematoma size. The evidence clearly shows this aggressive approach provides no benefit while increasing cost, procedural time, and patient discomfort 1, 2.