Topical anaesthetic (EMLA) 60 minutes prior for needle-based trephination
Background
Epidemiology
Incidence and prevalence
One of the most common hand injuries in the ED and primary care settings
No precise population incidence reported; crush injuries to digit are ubiquitous
Associated distal phalanx fracture rate
~25% of subungual hematomas have associated fracture
AFP (2022): Childress et al., common finger fractures review
Fingertip injuries overall prevalence
Account for up to 10% of all acute hand injuries in the ED
Most common occupational hand injury
Demographics
Any age affected; pediatric crush injuries (doors) extremely common
Occupational predominance: carpenters, mechanics, construction workers
Athletic populations: ball sports, rock climbing, racquet sports
Runners: repetitive microtrauma to toenails (runner's toe)
ICD-10 coding
S60.10 — contusion of unspecified finger (unspecified nail)
S60.11 through S60.19 — contusion of specific fingers
L60.8 — other nail disorders (subungual hematoma without fracture)
S62.5 — fracture of distal phalanx (when associated fracture present)
Pathophysiology
Mechanism of hematoma formation
Crush or direct blow compresses the highly vascularized nail bed against the rigid distal phalanx
Nail bed (sterile matrix and germinal matrix) is rich in glomus bodies
Rapid pressure rise causes rupture of nail bed microvasculature
Blood accumulates in the subungual space between nail plate and nail bed
Enclosed space creates pressure-related throbbing pain
Hematoma may dissect proximally under the nail fold
Nail anatomy relevant to pathophysiology
Germinal matrix: proximal nail bed responsible for 90% of nail plate production
Injury here causes permanent nail deformity
Sterile matrix: distal nail bed that adheres nail plate
Lacerations here most commonly repaired to preserve cosmetic outcome
Nail plate: keratin structure that protects sterile matrix
Acts as protective roof; disruption exposes nail bed
Hyponychium: seal at distal free edge; barrier to infection
Paronychium: lateral nail fold; paronychia can complicate nail injuries
Fracture mechanism
Tuft fracture: comminuted fracture of distal phalanx under crush load
Periosteum usually intact — closed fracture in most cases
Nail plate acts as biologic splint for nail bed
Open fracture scenario: nail plate displacement exposes fracture site
Any nail plate disruption with underlying fracture = potential open fracture
Seymour fracture: physeal plate shear with interposed soft tissue
Therapeutic Considerations
Trephination evidence base
Seaberg et al. (Am J Emerg Med, 1991): prospective study of trephination
Trephination alone yielded excellent outcomes regardless of hematoma size
No benefit from nail removal when nail plate intact and no associated nail fold injury
Traditional 50% rule (remove nail if >50% size): not supported by current evidence
AFP guideline (2025, Hilgefort et al.): nail integrity, not size, drives management decision
Non-operative management of nail bed injuries
Annals Plastic Surgery (2022): non-operative management compared to standard nail bed repair
Comparable functional and cosmetic outcomes at follow-up
Reduced procedural complexity and patient discomfort
Evidence supports observation for intact nail plate even when fracture is present
Infection risk following trephination
Infection rate from trephination is low when performed aseptically
No evidence that routine antibiotics after trephination reduce infection
Open fractures are a distinct indication for prophylactic antibiotics
Electrocautery safety
Western J Emergency Medicine (2022, Blereau et al.): acrylic nail ignition study
41.5% ignition rate with electrocautery near acrylic nails
Use 18-gauge needle or heated paperclip for acrylic nail patients
Nail regrowth and cosmesis
Fingernail grows approximately 3 mm/month; complete regrowth 3-6 months
Toenail grows approximately 1.5 mm/month; complete regrowth 6-12 months
Cosmetic outcome after trephination alone is generally excellent
Nail may fall off spontaneously as hematoma resolves
Patient Discharge Instructions
copy discharge instructions
Diagnosis and procedure explanation
You have a subungual hematoma — a blood blister under your nail caused by a crush or impact injury
A small hole was made in your nail (trephination) to drain the blood and relieve pressure
The nail may fall off on its own over the coming weeks — this is expected
A new nail will grow back; this typically takes 3-6 months for fingernails and 6-12 months for toenails
Wound and nail care instructions
Keep the finger elevated above heart level for the first 48 hours to reduce swelling
Apply ice wrapped in cloth for 20 minutes every 1-2 hours for the first 24 hours
Keep the wound clean and dry; change dressing every 24-48 hours
Soak in warm soapy water twice daily starting 48 hours after the procedure
Leave any sutures in place as directed; follow-up for removal if non-absorbable sutures placed
Activity restrictions
Avoid activities that stress the injured digit until pain resolves
Return to sport and heavy manual work as tolerated — no fixed restriction for trephination alone
If a fracture or tendon injury was also diagnosed, follow the specific instructions given
Medications
Take ibuprofen 400-600 mg every 6-8 hours with food for pain (unless told otherwise)
Acetaminophen 500-1000 mg every 6-8 hours can be alternated if needed
Do not exceed recommended doses of acetaminophen (max 4000 mg per day)
Continue any prescribed antibiotics for the full course
Return to emergency department immediately if
Increasing pain, redness, swelling, or warmth in the finger
Pus or foul-smelling discharge from the nail or wound
Fever above 38 degrees Celsius
Numbness or tingling that is getting worse
Inability to bend or straighten the fingertip
Streak of redness spreading up the finger or hand
Follow-up
Wound check appointment in 1-2 weeks
Repeat X-ray at follow-up if a fracture was identified
Return to see your family doctor if the nail does not regrow normally or the digit remains painful
A non-healing or pigmented area under the nail that was not caused by trauma should be seen by a dermatologist
References
Guidelines and key sources
Fingertip Injuries (AFP, 2025)
Hilgefort J, Becker J, Chu J
American Family Physician, 2025
PMID: 40736493
Approach to Nail Trauma for Primary Care Physicians (Can Fam Physician, 2023)
Lafreniere AS, Misati G, Knox A
Canadian Family Physician, 2023
PMID: 37704235
Fingertip Injuries: A Review and Update on Management (JAAOS, 2024)
De Ruiter BJ, Finnan MJ, Miller EA, Friedrich JB
Journal of the American Academy of Orthopaedic Surgeons, 2024
PMID: 39602800
Treatment of Subungual Hematomas With Nail Trephination (Am J Emerg Med, 1991)
Seaberg DC, Angelos WJ, Paris PM
American Journal of Emergency Medicine, 1991
PMID: 2018587
Supporting references
Common Finger Fractures and Dislocations (AFP, 2022)
Childress MA, Olivas J, Crutchfield A
American Family Physician, 2022
PMID: 35704814
Rethinking the Need for Nail Plate Removal (Ann Plast Surg, 2022)
Rao V, Akiki RK, Crozier JW, et al
Annals of Plastic Surgery, 2022
PMID: 35513322
Salter-Harris Fractures of the Distal Phalanx (Plast Reconstr Surg, 2018)
Gibreel W, Charafeddine A, Carlsen BT, Moran SL, Bakri K
Plastic and Reconstructive Surgery, 2018
PMID: 30148775
Dermoscopy of Subungual Haemorrhage (Br J Dermatol, 2013)
Mun JH, Kim GW, Jwa SW, et al
British Journal of Dermatology, 2013
PMID: 23302009
Up in Flames: Electrocautery Trephination Safety With Acrylic Nails (West J Emerg Med, 2022)
Blereau C, Radloff S, Grisham J
Western Journal of Emergency Medicine, 2022
PMID: 35302451
Subungual Tumors: US and MRI Findings (Radiographics, 2010)
Baek HJ, Lee SJ, Cho KH, et al
Radiographics, 2010
PMID: 21071379
Management of Simple Nail Bed Lacerations and Subungual Hematomas in the ED (Pediatr Emerg Care, 2014)
Patel L
Pediatric Emergency Care, 2014
PMID: 25275357
Tetanus (Lancet, 2026)
Ergonul O, Kolsuz S, Figueroa JP
Lancet, 2026
PMID: 41544646
Antibiotic Prophylaxis in Trauma (J Trauma Acute Care Surg, 2024)
Coccolini F, Sartelli M, Sawyer R, et al
Journal of Trauma and Acute Care Surgery, 2024
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