Chapter 102. Subungual Hematoma Evacuation

The fingertips are sensitive, mobile, and prone to injury. Blunt trauma to the tip of the finger or toe may result in a variety of injuries including fractures, avulsions to the nail and nail apparatus, contusions, lacerations, and amputations. The most common injuries to the distal fingers and toes are crush injuries. The most common mechanisms of injury are closure of some type of door (car, house, etc.) on the finger, dropped objects on the fingers or toes, hand tools, and power tools.

Subungual hematomas often develop following blunt trauma to the distal finger or toe.1–3 They result from the accumulation of blood between the nail and the nail bed. Treatment of a subungual hematoma is relatively straightforward, yet in some cases it is still controversial. It is important to understand the structure of the distal finger or toe, to determine whether simple drainage will be sufficient management, and to consider how initial management may affect outcome.

The distal digits of the fingers and toes and the nail apparatus are complex structures (Figure 102-1). The perionychium is composed of the nail bed and the surrounding soft tissue. The hyponychium is the junction of the nail bed at the sterile matrix and the fingertip skin beneath the distal margin of the nail. The eponychium is the distal portion of the nail fold where it attaches to the proximal surface of the nail. The lunule is the white arc seen in the proximal portion of the nail. The nail bed consists of the germinal matrix on the proximal ventral floor of the nail fold and the sterile matrix, which extends from the lunule to the hyponychium. The germinal matrix is primarily responsible for the growth of the nail, with a significant contribution from the sterile matrix.4,5 The nail bed must be smooth for normal nail growth. A nail matrix that has not been well approximated to minimize scar formation may develop a deformed nail.1,3–8

The nail bed receives its blood supply from the two terminal branches of the volar digital artery, which communicate to form blood sinuses. Venous drainage begins at the proximal portion of the nail bed and the skin proximal to the nail fold.4

Force applied to the tip of the finger or toe disrupts the vascular structures in the nail bed. Trauma causes the capillaries of the nail bed to be compressed between the nail and the distal phalanx. Blood collects between the nail bed and the nail, forming a subungual hematoma (Figure 102-2). The patient's pain is directly related to the injury itself and the increased pressure from the hematoma. The hematoma appears as a black-and-blue or black-and-purple area under the nail that is extremely tender to palpation.

Nail bed injuries may be classified as simple lacerations, stellate lacerations, severe crush injuries, and avulsions.1 It is important to understand that each of these types of nail bed injuries may result in a subungual hematoma.

The management of subungual hematomas is still somewhat controversial. The approach to management was initially very aggressive, since subungual hematomas are often seen with fractures of the distal phalanx, damage to the nail, and damage to the nail apparatus.1,2,4–8 The surgical literature generally recommends removal of the nail, inspection of the nail bed, and repair of any nail bed injury if the subungual hematoma involves 25% or more of the nail surface.1,2,4–9 This practice has been questioned recently by newer controlled studies that demonstrated excellent outcomes in patients with large (greater than 25%) subungual hematomas treated by trephination alone, regardless of the presence of fractures.11,12 Larger hematomas involving over 50% of the nail surface may be treated successfully with trephination. Many authors, primarily Hand Surgeons, still advocate the removal of the nail plate to thoroughly inspect the nail bed and effect repair in all patients who present with a subungual hematoma. Although this approach is time-honored, more recent studies have demonstrated that it is not necessary if the patient's nail is still attached to the matrix, even in the presence of a distal phalanx fracture.11,12

Patients who present to the Emergency Department after sustaining an injury with a resultant subungual hematoma will generally complain of severe pain. Trephination, the process of making a small hole in the nail to allow the collected blood to escape, will provide significant relief for most patients.2,9 The trephination procedures described below should be utilized when patients present with a subungual hematoma and an intact (not fractured or avulsed) nail plate that is still attached to the matrix. If the nail plate is partially or completely avulsed from the matrix, simple evacuation of the hematoma may not constitute adequate therapy.9,10,11,13

Simple trephination is reserved for patients with intact nails. Patients who present with nail plate fractures, avulsions of the nail plate, disruption of the nail margin, or partial amputations may require more extensive therapy with removal of the nail plate and repair of the nail bed. A description of these techniques is provided in Chapters 96 and 104. Trephination using heat-based methods should be avoided in patients wearing artificial nails due to the potential for igniting the nail or nail adhesive.13 Subungual hematomas that extend proximal to the nail bed often represent proximal nail plate avulsions or injuries that require nail plate removal, nail plate repair or reinsertion, and nail bed repair.

Digital/Metacarpal Block

• Povidone iodine or chlorhexidine solution, or an isopropyl alcohol pad
• 3 mL syringe
• 25 or 27 gauge needle, 1 in. long
• Local anesthetic solution without epinephrine

Electrocautery

• Povidone iodine or chlorhexidine solution, or an isopropyl alcohol pad
• Battery-powered electrocautery device

Paper Clip Technique

• Povidone iodine or chlorhexidine solution, or an isopropyl alcohol pad
• Heat source (open flame)
• Paper clip
• Hemostat

Drill Technique

• Povidone iodine or chlorhexidine solution, or an isopropyl alcohol pad
• 18 gauge needle
• Cotton-tipped applicators

The PathFormer (Path Scientific, Carlisle, MA) is an FDA approved device for nail plate trephination. It allows for the precise control of the depth of penetration while making a 400 μm diameter hole in the nail plate. The device is a battery-powered drill that automatically retracts the drill bit after the nail plate is penetrated. Thus, the sensitive and vascular nail bed is not contacted or injured. Unfortunately, the PathFormer device is not often available in Emergency Departments.

Explain the procedure to the patient and emphasize that pain relief rapidly follows nail trephination. Obtain a consent to perform the procedure. Consider obtaining radiographs for significant traumatic injuries, suspected associated fractures, or any injury where the nail plate is damaged or avulsed. Place the patient in a sitting or semi-recumbent position on a gurney or multipositional procedure chair. Sit facing the patient. Place the hand with the injured digit palm side down on a flat surface such as a procedure table. Cleanse the injured digit of any dirt and debris. Apply povidone iodine or chlorhexidine solution over the nail plate and allow it to dry. An alcohol swab is an alternative to these solutions. Always allow the alcohol to dry before touching the nail plate with a hot object so that the alcohol does not ignite. A digital block is generally not needed if using heat-based methods to penetrate the nail plate.2,5,9,13 The nail plate is not innervated and the hematoma prevents contact with the nail bed. A digital block may be required if the patient is excessively anxious, if additional injury is present, or if a drill technique is to be performed. Refer to Chapter 126 for the complete details regarding digital and metacarpal blocks. An alternative to the digital block is to soak the affected finger in ice water for a few minutes prior to the procedure. The techniques described below may be used on fingernails and toenails.

Electrocautery Technique

Electrocautery is the preferred technique to drain a subungual hematoma. Battery-operated microcautery devices are generally available in the Emergency Department (Figure 102-3). Assure the patient that they will not be burned. Stabilize the injured digit proximally with the nondominant hand. Grasp the cautery unit like a pencil with the dominant hand. Press the button on the cautery unit to heat the tip. Release the button and allow the tip to cool for 1 to 2 seconds. This may prevent penetrating the nail plate too quickly and damaging the underlying nail bed. Place the hot tip on the nail plate, centered over the hematoma (Figure 102-4). Tap the nail plate several times with the cautery pen tip. Do not constantly hold the hot tip against the nail plate. The cautery tip will easily penetrate the nail plate. Do not plunge as the nail bed can be injured in addition to causing additional pain to the patient.

Darkened blood will flow out of the hole when the hematoma is entered. The nail will regain its normal color after the hematoma is drained. Apply slight digital pressure to the nail plate to ensure complete drainage of the hematoma. The patient will usually begin to feel pain relief at this point.

The tips of some microcautery devices are shaped in such a way that they will not make a hole that is wide enough to allow adequate drainage. Slightly rotate the cautery unit as it traverses the nail plate to ensure an adequate sized drainage hole of 3 to 4 mm. Some Emergency Physicians prefer to make an additional hole in the nail plate to ensure drainage if the first hole should become occluded. As an alternative to the single large hole, place three to four smaller drainage holes in the nail plate.

Paper Clip Technique

This technique is similar to that using the electrocautery unit. Unfold and heat the tip of a paper clip with a flame from a lighter or alcohol lamp. Place the heated tip of the paper clip against the nail plate, centered over the subungual hematoma (Figure 102-5). Apply slight downward pressure to allow the paper clip to perforate the nail plate. Do not plunge as the nail bed can be injured in addition to causing additional pain to the patient. A drop of blood will be seen as the paper clip enters the hematoma. Place at least one additional hole in the nail plate to ensure drainage if the first hole should become occluded.

The paper clip will not get as hot as a cautery device. More than one attempt may be necessary to penetrate a thick nail. Another disadvantage of this technique is the possibility of introducing carbonaceous material into the hole. The use of an open flame may be potentially dangerous or prohibited in the Emergency Department.

Drill Technique

This technique uses a needle as a small drill to penetrate the nail plate (Figure 102-6). Small electric nail drills are available that greatly simplify this procedure, though they may not be readily available in the Emergency Department. Drilling through the nail plate may require a digital block. This is particularly true if there is a fracture, another associated injury, or the nail plate is very thick. Grasp an 18-gauge needle by its hub with the dominant thumb and forefinger (Figure 102-6A). Place the tip of the needle over the nail plate, centered over the subungual hematoma. Spin the needle back and forth while applying gentle downward pressure. Small shavings will appear as the needle begins to drill through the nail plate. A loss of resistance will be felt as the hematoma is entered and darkened blood will flow from the hole. Do not plunge as the nail bed can be injured in addition to causing additional pain to the patient. Place at least one additional hole in the nail plate to ensure drainage if the first hole should become occluded.

The editor uses a modified version of this technique (Reichman, personal communication). A cotton-tipped applicator may be wedged into the needle hub to facilitate the drilling (Figure 102-6B). This method makes the drilling more efficient, as the cotton-tipped applicator is easier to hold and offers a mechanical advantage when it is twisted. The drill technique is very useful in the absence of a heat-generating device.

Gently compress the nail plate to evacuate the hematoma. Any underlying injury should be evaluated and managed.

The patient should keep the wound clean and monitor drainage. The nail plate may be covered with a nonadherent dressing. The hematoma may continue to drain for several hours or up to 1 to 2 days. If there is a reaccumulation, denoted by the reappearance of darkened blood beneath the nail, the nail can be soaked in warm water and pressure applied to express the hematoma. Inform the patient that the discoloration under the nail plate can persist for several weeks. Also inform them that the nail plate may fall off and it can take up to 3 months for another nail plate to completely form. A splint should be applied if a distal phalanx fracture is present. No studies have demonstrated that prophylactic antibiotics are beneficial in the management of a subungual hematoma.9,14 The patient should immediately return to the Emergency Department or their primary physician for fever, increased pain, purulent drainage from the nail, or any redness or swelling of the digit.

Direct complications from nail trephination are rare.11–13 Complications will more likely result from the original injury and include nail loss, nail deformity, cosmetic changes, and infection. Patients should be warned that as the nail grows out, loss of the nail is a possibility. The hematoma may reaccumulate if the hole in the nail is too small and becomes occluded. Reaccumulation can be prevented by making a large hole or multiple holes in the nail plate. Plunging through the nail plate with a cautery unit or needle will cause the patient pain and injury to the nail bed that may be permanent and result in a deformed nail plate.

Fingertip injuries are common. Patients will often present to the Emergency Department with a subungual hematoma and a complaint of pain. Rapid relief of pain and good outcomes can be obtained in the majority of cases by simply performing a nail trephination. It is important to distinguish when trephination alone will not be adequate therapy. Patients presenting with nail plate fractures, avulsions of the nail plate, or partial finger amputations will require removal of the nail plate and repair of the nail bed.