- Collection of blood under the nail
- There is a strong association with distal phalanx fractures.
- In the past, complete nail removal and exploration and closure of possible nail bed lacerations was performed. A prospective study of 52 children supports management with trephination alone for any size hematoma.
- Atraumatic subungual hematoma may be caused by melanoma or Kaposi's sarcoma
- Simple: No nailbed dislocation or evidence of open fracture
- Complex: Aassociated with fracture or nail plate disruption
- The perinychium includes the nail, the nailbed, and the surrounding tissue.
- The paronychia is the lateral nail folds
- The hyponychium is the palmar surface skin distal to the nail.
- The lunula is that white semi-moon shaped proximal portion of the nail.
- The sterile matrix is deep to the nail, adheres to it and is distal to the lunule.
- The germinal portion is proximal to the matrix and is responsible for nail growth.
- Blood trapped under nail
- Subungual hematoma
- Distal Phalanx (Finger) Fracture
- Nailbed laceration
- Finger amputation
- Fingertip laceration
- Nail avulsion
- Finger infection
- Distal interphalangeal dislocation (finger)
- Distal finger
- Other finger/thumb
- Clinical diagnosis
- Evaluate percentage of nail bed involved, test extensor/flexor tendons and distal cap refill
- Cleanse with povidone-iodine solution (not flammable alcohol)
- Handheld cautery works best - no anesthesia is required
- Alternatively a needle spun in a drilling fashion
- Sharp object (i.e. safety pin) heated with flame in an austere environment
- If a fracture is present, the digit should be splinted
- Instruct patients to soak affected finger in warm water BID-TID x7d
- Prophylactic antibiotics are not needed after trephination of uncomplicated hematomas 
- Nail removal only recommended if there is associated nail avulsion or nail fold disruption
- Repair nailbed laceration using absorbable sutures
- Presence of acrylic nails secondry to fire risk. Remove acrylic nails before using electrocautery tool.
- Roser SE, Gellman H. Comparison of nail bed repair versus nail trephination for subungual hematomas in children. J Hand Surg. 1999;24(6):2266-1170.
- Holtzman L. Incision and Drainage. In: Roberts and Hedges' Clinical Procedures in Emergency Medicine. 6th ed. Philadelphia, PA: Elsevier; 2014.
- Seaberg DC, ANgelos WJ, et al. Treatment of subungual hematomas with nail trephination: a prospective study. Am J Emerg Med. 1991; 9(3):209-210