A subungual hematoma is a collection of blood beneath the nail plate, most commonly resulting from crush or blunt trauma to the fingertip or toe. It is one of the most frequently encountered hand injuries in the emergency department and primary care settings. [1-2] The condition is diagnosed clinically and managed with observation or nail trephination depending on symptoms and size. [1]
1. History
- Mechanism of injury: Crush injury (e.g., door, hammer, heavy object), direct blow, or axial load — the most common mechanisms [2-3]
- Timing: When did the injury occur? Acute vs. delayed presentation affects management options
- Symptom characterization: Throbbing pain under the nail, pressure sensation, discoloration (dark red/purple/black beneath nail)
- Dominant hand: Functional impact and occupational relevance
- Prior treatment attempts: Ice, elevation, self-drainage
- Tetanus immunization status: Essential for all traumatic wounds [4-5]
- Anticoagulant or antiplatelet use: May affect bleeding extent
- Occupational/recreational context: Manual laborers, athletes, musicians — higher functional demands
2. Alarm Features
- Nail plate disruption, avulsion, or surrounding nail fold injury → suggests underlying nail bed laceration requiring exploration and repair [6-7]
- Significant deformity or angulation of the digit → displaced fracture, possible tendon injury
- Inability to extend the DIP joint → mallet finger (extensor tendon disruption) [1][8]
- Inability to flex the DIP joint → jersey finger (FDP avulsion) — requires urgent surgical referral [1]
- Neurovascular compromise: Absent capillary refill, loss of 2-point discrimination [7]
- Open wound with exposed bone → open fracture requiring antibiotics and possible operative management [5][9]
- Seymour fracture (pediatric): Salter-Harris I/II fracture of the distal phalanx with nail plate subluxation from the eponychial fold — technically an open fracture requiring surgical exploration [7][10]
- Non-traumatic subungual pigmentation or pigmentation that does not migrate distally with nail growth → consider subungual melanoma [11-12]
3. Medications
- Analgesics: NSAIDs (ibuprofen 400–600 mg PO q6–8h) or acetaminophen for pain control
- Tetanus prophylaxis: Tdap if last booster >5 years ago for dirty/contaminated wounds, or >10 years for clean wounds [4-5]
- Antibiotics: Not routinely indicated for simple subungual hematoma. Consider a first-generation cephalosporin (e.g., cephalexin) if there is an associated open fracture [5][9]
- Caution with anticoagulants/antiplatelets: May increase hematoma size; do not discontinue without appropriate risk-benefit assessment
- Avoid electrocautery trephination in patients with acrylic nails — 41.5% ignition rate in a simulation study [13]
4. Diet
- No specific dietary modifications are required for subungual hematoma
- Adequate protein and vitamin C intake support wound healing in the recovery phase
- Hydration is generally supportive
5. Review of Systems
- MSK: Pain with grip, range of motion at DIP joint (flexion and extension), finger stiffness
- Neuro: Numbness or tingling in the fingertip (digital nerve injury)
- Vascular: Cold intolerance, color changes (consider vascular injury)
- Derm: Nail changes, pigmentation patterns, prior nail dystrophy
- Constitutional: Fever (if presenting late — concern for infection/osteomyelitis)
- Heme: Easy bruising, bleeding history (coagulopathy screen)
6. Collateral History and Family History
- Collateral: Witnesses to mechanism (especially in pediatric patients — consider non-accidental trauma if mechanism inconsistent with injury pattern)
- Family history: Generally not contributory; however, bleeding disorders (hemophilia, von Willebrand disease) may predispose to larger hematomas from minor trauma
- Social context: Occupation (manual labor, musician), hand dominance, sports participation
7. Risk Factors
- Occupational exposure: Carpenters, mechanics, construction workers, industrial workers
- Sports: Ball-handling sports (basketball, football), racquet sports, rock climbing
- Pediatric patients: Crush injuries from doors are extremely common [14]
- Anticoagulant/antiplatelet therapy: Larger hematomas from minor trauma
- Acrylic or artificial nails: Complicate trephination technique [13]
- Repetitive microtrauma: Runners (toenails — "runner's toe"), ill-fitting footwear
8. Differential Diagnosis
- Nail bed laceration: Often coexists; suspect when nail plate is disrupted or hematoma >50% with associated fracture [6][15]
- Distal phalanx fracture (tuft fracture): ~25% of subungual hematomas have an associated fracture; subungual hematoma with fracture may represent an open fracture [8][16]
- Mallet finger: Extensor tendon disruption — inability to actively extend DIP [1]
- Jersey finger: FDP avulsion — inability to flex DIP; requires surgical referral [1]
- Subungual melanoma (cannot-miss): Non-traumatic pigmentation, Hutchinson sign (periungual pigmentation), longitudinal irregular bands on dermoscopy; does NOT migrate with nail growth [11-12][17]
- Glomus tumor: Paroxysmal pain, cold sensitivity, point tenderness (Love's test); bluish-red discoloration under nail [18-19]
- Subungual exostosis: Bony growth under nail, progressive nail deformity [20]
- Onychomycosis: Chronic nail discoloration/dystrophy — can mimic chronic subungual hemorrhage
- Splinter hemorrhages: Linear, longitudinal; associated with endocarditis, vasculitis, psoriasis, trauma [21]
9. Past Medical History
- Prior fingertip injuries or nail deformities
- Bleeding disorders or anticoagulant use
- Diabetes (impaired healing, infection risk)
- Peripheral vascular disease
- Immunosuppression
- Prior hand surgery
- Tetanus immunization history
10. Physical Exam
- Inspection: Dark red, purple, or black discoloration beneath the nail plate; assess percentage of nail involved; evaluate nail plate integrity and surrounding nail folds for disruption [7]
- Palpation: Point tenderness over the nail; assess for tenderness over the distal phalanx (fracture)
- Neurovascular exam: Pulp capillary refill, 2-point discrimination (normal <6 mm), compare with contralateral uninjured digit [7]
- Range of motion: Active flexion and extension at the DIP joint — critical to rule out mallet finger (no active extension) and jersey finger (no active flexion) [1]
- Nail plate stability: Assess for subluxation from the eponychial fold (Seymour fracture in children) [7][10]
- Rotational alignment: With fingers flexed, all fingertips should point toward the scaphoid; malrotation suggests an unstable fracture
11. Lab Studies
- Routine labs are not indicated for simple subungual hematoma
- If concern for infection (delayed presentation): CBC, CRP/ESR
- If concern for coagulopathy: PT/INR, PTT, platelet count
- Wound culture if signs of secondary infection
12. Imaging
- X-ray (AP and lateral of the digit): Recommended for all subungual hematomas to evaluate for distal phalanx fracture. Approximately 25% of subungual hematomas have an associated fracture [3][16][22]
- Key findings: Tuft fracture (comminuted distal phalanx), transverse shaft fracture, intra-articular involvement, avulsion fragments
- Point-of-care ultrasound: Can detect nail bed lacerations beneath an intact nail plate, potentially avoiding unnecessary nail removal [1]
- MRI: Not indicated acutely; reserved for suspected subungual tumors (glomus tumor, melanoma) [20]
- Imaging is unnecessary if the injury is clearly minor with minimal hematoma and no clinical suspicion of fracture
13. Special Tests
- Love's test: Pinpoint pressure over the nail reproduces pain — positive in glomus tumor [19][23]
- Hildreth's test: Tourniquet applied to the digit relieves pain — suggestive of glomus tumor
- Cold sensitivity test: Pain with cold exposure — glomus tumor triad (paroxysmal pain, cold sensitivity, point tenderness) [23]
- Dermoscopy: Useful for distinguishing subungual hemorrhage from melanoma — hemorrhage shows homogeneous pattern with peripheral fading; melanoma shows Hutchinson sign, irregular longitudinal bands, and ulceration [11]
- Migration test: Subungual hemorrhage migrates distally with nail growth over weeks; melanocytic lesions do not [12]
14. ECG
- Not applicable for isolated subungual hematoma
- No indication for ECG unless there is a concurrent systemic condition or polytrauma
15. Assessment
Subungual hematoma is a clinical diagnosis based on the presence of dark blood beneath an intact or disrupted nail plate following trauma. [1] Severity stratification:
- Simple: Intact nail plate, no nail fold disruption, no fracture → trephination alone is sufficient [6][22]
- Complex: Nail plate disruption, nail fold injury, or associated displaced/open fracture → nail removal, nail bed exploration, and repair may be required [6-7]
- Pediatric Seymour fracture: Physeal fracture with nail plate subluxation — open fracture requiring surgical exploration, irrigation, and antibiotics [10]
Key pearl: The historic teaching that hematomas >50% require nail removal has been largely debunked. Prospective data show that trephination alone yields excellent outcomes regardless of hematoma size, even with associated non-displaced fractures, as long as the nail plate and nail folds are intact. [6][22][24]
16. Treatment Plan
Initial stabilization:
Nail trephination (for painful hematomas):
- Electrocautery (handheld battery-operated cautery): Preferred method — melt through the nail plate until blood drains; no anesthesia typically needed [6][22]
- 18-gauge needle: Manual rotation through the nail plate — alternative technique
- Heated paperclip: Traditional method, effective but less controlled
- 29-gauge needle via hyponychium: Alternative for smaller hematomas, especially toenails [25]
- Contraindication: Avoid electrocautery with acrylic/artificial nails (fire risk) — use needle technique instead [13]
- All patients in the Seaberg et al. prospective study reported immediate pain relief after trephination, with no infections, osteomyelitis, or nail deformities at mean 10-month follow-up [22]
When to remove the nail and repair the nail bed:
- Disrupted or avulsed nail plate [6-7]
- Disrupted nail folds (especially the eponychial fold) [6]
- Seymour fracture in children [10]
- Nail bed repair is performed with 6-0 or 7-0 absorbable sutures (chromic gut or Vicryl Rapide) under digital block and tourniquet [7][14]
Associated fracture management:
- Non-displaced tuft fractures: Protective splinting (DIP in extension) for 4–6 weeks [8]
- Open fractures: Antibiotics (first-generation cephalosporin), tetanus prophylaxis, and possible operative management [5][9]
- Referral indications: Open fractures, intra-articular fractures involving >1/3 of the articular surface, displaced/angulated fractures, mallet finger with >30% articular involvement, all jersey finger injuries [1][8]
Observation alone is appropriate for small, painless subungual hematomas. [1]
17. Disposition
- Discharge: The vast majority of subungual hematomas — simple trephination and follow-up [22]
- Observation: Not typically required
- Admission: Essentially never for isolated subungual hematoma
- Specialist consultation triggers:
- Hand surgery: Complex nail bed lacerations, displaced/open fractures, Seymour fractures, jersey finger, mallet finger with large bony fragment [1-2]
- Dermatology: Suspected subungual melanoma or glomus tumor [12][19]
18. Follow Up / Return Precautions
- Follow-up timing: 1–2 weeks for wound check; every 2 weeks if associated fracture until healed (typically 4–6 weeks) [8]
- Nail regrowth: Average 4 months (range 2–7 months); fingernails grow faster than toenails [22]
- Return precautions — advise patients to return for:
- Increasing pain, swelling, redness, or purulent drainage (infection)
- Fever
- Inability to bend or straighten the fingertip (missed tendon injury)
- Numbness that worsens or does not improve
- Nail that does not regrow normally or develops persistent deformity
- Counseling: The nail will likely fall off and regrow; cosmetic result is generally excellent after trephination alone. Temporary nail discoloration and irregularity during regrowth is expected. [22][24]
- Non-traumatic pigmented nail lesions that do not migrate with nail growth warrant dermatology referral to rule out melanoma [11-12]
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