Subungual hematomas are common. Here’s an essential guide on how and when to drain them:
Trephination Indications
Use nail trephination (drilling) for subungual hematomas that are painful or cover >25% of nail area and are <48 hours old. It relieves pain and prevents nail dystrophy or secondary infections (Source).
Nail Removal Indications
In the past, nail removal was recommended for large hematomas, but several studies showed equal efficacy for trephination. Today, it is only recommended for nail avulsion, proximal fractures or dislocated distal fractures.
Hematoma Diagnosis
Look for sudden pain after nail trauma and sharp-edged color changes that progress distally over time. DD: subungual melanoma.
Further Examination
Radiographs may be necessary as fractures are common. Fractures would require antibiotics (they are essentially open fractures) but do not contraindicate trephination.
Preparation
Clean and disinfect thoroughly. Some recommend a digital block with lidocaine, though others suggest it’s more painful than the procedure itself. Use personal protection as blood may spread.
Equipment & Method
Pfenninger & Fowler’s, StatPerls, PraxisSkills and JAAD prefer one of these methods:
- Drilling: twist a needle or scalpel between your fingers.
- Electrocautery: apply the cautery tip to create a hole.
- Paperclip: heat it over an open flame until red, press firmly, and stop immediately when perforated to protect the nail bed.
- Biopsy punch: perforate with a biopsy punch instrument or curette.
- Here are short videos on trephination with electrocautery and with a needle.
Complications
Loss of nail (temporary), hematoma recurrence (common), infection, pain, and not recognizing a fracture.
Conclusion
- Make the hole 1-2mm wide to prevent it from closing off within hours.
- Apply antibiotic ointment to prevent infection but also to avoid blood clotting.
- Avoid sudden movements in children and anxious patients by making the intervention invisible (work through the fibers of a gauze).
- Preserve the nail as long as possible as it’s the best protection for the nail bed. Cover possible nail loss with an artificial nail if necessary.
- Keep in mind that acrylic nails are flammable, as an interesting 2022 study
