Subungual Hematoma Drainage

E. J. Mayeaux, Jr, MD, DABFP, FAAFP
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Introduction

Subungual hematoma is a common injury, usually caused by a blow to a distal phalanx, such as crushing a finger in a doorjamb or stubbing a toe. The blow causes bleeding of the nail matrix or nail bed, with subsequent subungual hematoma formation. The traumatic accumulation of blood beneath the nail plate can create an excruciatingly painful injury. The often pulsatile pain is caused by increased pressure of the blood within a closed space adjacent to the sensitive nail bed and matrix. Subungual hematomas frequently manifest with a blue-black discoloration that can extend beneath part or all of the nail surface. The pain of a subungual hematoma can be dramatically and instantaneously relieved by drainage. 
Trephination provides a simple technique to evacuate hematomas. Various techniques have been advocated, including the use of heated paper clips, scalpel blades, dental burrs, and cautery units. Because the nail plate has no sensation, anesthesia generally is not required. Care should be exerted with any trephination instrument, because downward pressure increases pain. The use of a hot-tipped cautery unit is advocated because it burns a hole through nail plate without the need for much downward pressure or mining. The examiner must be prepared to lift up immediately on passage through the nail plate to avoid injury to the sensitive nail bed. 
Over time, the tissues surrounding the hematoma stretch, and the pain subsides. There appears to be little pain relief obtained from draining a hematoma after about 48 to 72 hours following the initial injury. The discoloration of a subungual hematoma will grow out with the nail and be replaced with normal-appearing tissues. 
Up to 25% of all subungual hematomas are associated with a fracture of the distal phalanx. Fractures are more likely to be present in patients with hematomas involving at least 50% of the nail bed, and some providers advocate routine x-ray examination, especially in children. If fracture is identified, 60% of those nails will have a laceration large enough to warrant closure with a small, absorbable suture. The major incentive to nail bed exploration and laceration repair is to prevent permanent nail dystrophy or deformity from a step-off or separated laceration. 
Appropriate management of a subungual hematoma seeks to provide pain relief, recognizes associated injuries, and promotes regrowth of a functionally normal and cosmetically acceptable nail. Historically, it was recommended that hematomas involving more than 25% to 50% of the nail surface be explored. Nail plate removal and nail bed exploration was advocated to optimize the cosmetic outcome. The routine practice of nail bed exploration has been questioned by several studies; it appears that the practice is justified only when a laceration is through the nail plate or through either of the lateral nail folds. If no laceration is detected, it is probably safe to evacuate the hematoma, although 1 in 12 patients still may experience residual nail change. 

Equipment

  • Fine-tipped battery cautery units

  • Needle, 19 gauge

  • A suggested surgical tray that can be used for laceration repair is listed in Appendix G

  • A suggested anesthesia tray that can be used for this procedure is listed in Appendix F

Indications

  • Severe pain with a subungual hematoma after acute traumatic injury

Contraindications

  • Patient is no longer experiencing pain at rest (after 48 to 72 hours)

  • Subungual ecchymosis (pain resolves after 30 minutes; only mild bleeding occurs)

  • Blood collection without trauma (tumors such as glomus tumors, keratoacanthomas, and Kaposi sarcoma may manifest initially as a subungual hematoma)

  • Subungual band of pigmentation (most likely represents nontraumatic benign or malignant pigmentation)

The Procedure

Step 1

Restrain the digit (and the child if he or she is uncooperative). Clean the nail with a prep solution (see Appendix E). Hold the fine-tipped cautery vertically over the center of the hematoma. Activate the cautery, and burn through the nail plate. 
  • PITFALL: As the nail plate is traversed, blood may spurt upward as the pressure is released. The provider should wear personal protective gear and make sure he or she is not directly over the device, where the risk of contamination is greatest.

Step 2

As soon as the subungual space is entered, the operator must be prepared to pull up and not allow the hot tip to touch down on the highly sensitive nail bed. 
  • Pearl: Create a hole large enough for continued drainage, which can occur for 1 to 2 days after the injury.

Step 3

Alternately, a heated steel paper clip also can accomplish the evacuation. The metal paper clip is straightened and grasped with a hemostat for heating and nail plate drilling as described previously. 
  • PITFALL: Avoid heating coated paper clips, which can produce a malodorous plume and burns from the molten coating. Avoid copper paper clips, which can melt.

Step 4

If a cautery unit or needle and heat source are not available, a 19-gauge needle can be placed on the nail plate and twisted. This causes the bevel of the needle to drill into the plate. 
  • PITFALL: Be careful to stop drilling as soon as blood starts draining to prevent the needle from contacting the nail bed.

Step 5

If the nail is torn or if there is a laceration through the lateral nail fold, the nail plate can be removed and the nail bed explored. Often, the nail matrix remains attached, whereas the distal nail may be separated from the nail bed. The distal nail can be cut free and the laceration in the nail bed repaired with a fine (6-0) absorbable (polyglycan, Vicryl) suture. 

Complications

  • Onycholysis

  • Nail deformity (often nail splitting)

  • Infection

  • Inadvertent burns

Pediatric Considerations

The procedure in children is essentially the same. Younger children may not be able to hold still, so restraining them may be necessary. Consider procedural sedation for nail bed exploration or repair (see Pediatric Sedation). 

Postprocedure Instructions

The site should be kept covered with a sterile gauze dressing while the wound continues to drain (1 to 2 days for trephination). The dressing should be changed daily. 
If the nail plate was removed, instruct the patient to soak the digit in clean water twice daily. After the soaks, apply a topical antibiotic ointment and a dry sterile bandage or adhesive bandage. 
If the nail matrix was repaired, the removed nail should be dressed and repositioned beneath the proximal nail fold to prevent permanent dystrophy from scarring of the proximal nail fold onto the underlying matrix. Some practitioners prefer to anchor the nail plate by suturing it to lateral tissues. Other materials, such as petroleum-impregnated gauze, plastic nails, or nonadherent or plastic dressings, can be used to separate the proximal nail fold from the nail matrix for 1 to 2 weeks after the procedure. 

Coding Information and Supply Sources

When evacuation of a hematoma is performed, usually only code 11740 is reported. 

Supply Sources

Bibliography

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Clark RE, Madani S, Bettencourt MS. Nail surgery. Dermatol Clin .  1998;16:145–164. [View Abstract]
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Fieg EL. Management of nail bed lacerations [Letter]. Am Fam Physician .  2002;65:1997B–1998.
Helms A, Brodell RT. Surgical pearls: prompt treatment of subungual hematoma by decompression. J Am Acad Dermatol.  2000;42:508–509. [View Abstract]
Roser SE, Gellman H. Comparison of nail bed repair versus nail trephination for subungual hematomas in children. J Hand Surg Am.  1999;24:1166–1170. [View Abstract]
Zuber TJ. Skin Biopsy, Excision, and Repair Techniques . Kansas City: American Academy of Family Physicians;  1998:76–81.
2008 MAG Mutual Healthcare Solutions, Inc.’s Physicians’ Fee and Coding Guide. Duluth, Georgia. MAG Mutual Healthcare Solutions, Inc. 2007.
 
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