Subungual hematoma

INTRODUCTION — Management of a simple subungual hematomas (ie, with intact nail fold and minimal nail or digit disruption) is discussed here. The evaluation and management of distal phalanx fractures and fingertip injuries are discussed elsewhere.

●(See "Distal phalanx fractures".)

●(See "Evaluation and management of fingertip injuries".)

DEFINITIONS — Subungual hematoma refers to blood that is trapped under the nail after trauma. Subungual hematomas may be simple (ie, the nail and nail fold are intact) (picture 1) or accompanied by significant injuries to the nail fold and digit (eg, fingertip avulsion) [1,2].

Trephination of a subungual hematoma consists of placing one or more holes in the nail to permit drainage of blood.

Subungual hematoma (blood under the fingernail or toenail), a common childhood injury, is usually caused by a blow to the distal phalanx (eg, crush in a door jamb, stubbing one's toe). The blow causes bleeding of the nail bed with resultant subungual hematoma formation. Patients complain of throbbing pain and blue-black discoloration under the nail as the hematoma progresses. Pain is relieved immediately for most patients with simple nail trephination.

ANATOMY — The nail matrix is the tissue under the base of the nail that permits nail growth and migration (figure 1). Its longitudinal fibers anchor the dermis to the periosteum of the distal phalanx [3]. The matrix begins 7 to 8 mm under the proximal fold, and its distal end is the white crescent called the lunula. Scarring of the matrix, as occurs with nail trauma, can disrupt nail growth and lead to nail deformity or permanent loss of the nail.

The richly vascularized nail bed lies directly beneath the plate to provide adherence and support and is the basis of the characteristic pink color. The proximal and lateral nail folds surround the plate on three sides. The cuticle, an outgrowth of the proximal fold, provides a seal between the fold and the nail plate (figure 1) [1].

When a subungual hematoma occurs, the source of pain is pressure in a contained space pressing against nerve fibers and not from the soft tissue injury or bony injury alone.

EVALUATION — Focused evaluation consists of physical examination of the involved digit and plain radiographs in patients with extensive nailbed injuries or large subungual hematomas:

●Physical examination – The involved digit should be evaluated for neurovascular compromise and inspected for evidence of nail fold disruption, deformity of the finger (including flexion at distal interphalangeal [DIP] joint and inability to extend it), or nail plate disruption including avulsion of the nail. Trephination is useful to relieve pressure on the nailbed from a hematoma formed in a closed space. If physical exam reveals a nail avulsion or bleeding around the nail fold, then trephination is not likely to offer relief. Trephination is contraindicated in patients with obvious deformity.

The extensor tendon should be specifically examined for evidence of tendon disruption at the DIP joint (mallet finger) (picture 2 and figure 2). (See "Extensor tendon injury of the distal interphalangeal joint (mallet finger)" and "Extensor tendon injury of the distal interphalangeal joint (mallet finger)", section on 'Symptoms and examination findings'.)

●Imaging – We suggest obtaining radiographs in all patients with extensive nailbed injuries or large subungual hematomas that occupy >50 percent of the nail plate because associated fractures are common with these injuries. (See "Distal phalanx fractures", section on 'Clinical presentation and physical examination' and "Evaluation and management of fingertip injuries", section on 'Evaluation'.)

Radiographs of the distal phalanx are warranted in most patients with subungual hematomas because fractures will require splinting and, if a displaced fracture is found, subspecialty referral. As an example, in one study of 47 patients with subungual hematoma, 32 percent also had distal phalangeal fractures [4]. Fractures were more likely to be present in patients with hematomas involving at least 50 percent of the nail bed than in those involving less (42 versus 0 percent). (See "Distal phalanx fractures", section on 'Diagnostic imaging'.)

A distal phalanx fracture associated with a subungual hematoma is an open fracture, which has implications for treatment. (See 'Prophylactic antibiotics' below.)

INDICATIONS

Trephination — The medical provider should trephinate subungual hematomas that are acute (less than 24 to 48 hours old), are not spontaneously draining (eg, blood oozing around the edge of the nail), are associated with intact nail folds, and painful.

In our experience, after 48 hours, most subungual hematomas have clotted, and trephination is typically not effective. Hematomas that occupy >50 percent of the nail warrant radiographs to assess for an underlying fracture. Trephination may be attempted after 48 hours in patients with severe pain. Nail removal is not beneficial and should be avoided as long as the nail and all nail folds are intact.

Nail removal — We suggest that patients with painful subungual hematomas and intact nail folds undergo trephination alone rather than nail removal and nail bed repair even when large hematomas or underlying fractures are present. Nail removal and nail bed laceration repair should occur when a nail laceration threatens the preservation of the nail or digit (eg, nail fold injury with marked laceration of the nail bed, typically in association with a fingertip or toe avulsion). Indications for nail removal and management of nail bed lacerations are discussed in detail elsewhere. (See "Evaluation and management of fingertip injuries", section on 'Choice of procedure'.)

Subspecialty consultation or referral — Most simple subungual hematomas can be managed by the emergency or primary care provider. The clinician should consult a hand surgeon if there is concern related to permanent deformity or loss of finger function, including patients with:

●Displaced fractures

●Salter-Harris fractures (ie, Seymour fractures)

●Intraarticular fractures

●Extensive nail bed injury

●Infected wounds

Indications for subspecialty consultation for patients with significant fingertip injuries are provided separately. (See "Evaluation and management of fingertip injuries", section on 'Indications for subspecialty consultation or referral'.)

CONTRAINDICATIONS AND PRECAUTIONS — Prior to trephination, the clinician should differentiate subungual hematoma from other conditions that have similar appearance. In many instances, these conditions can be readily distinguished from subungual hematoma by the lack of antecedent trauma , and the lesions will not be painful:

●Subungual melanoma – A subungual melanoma typically starts as a painless darkly pigmented band in the matrix and extends the length of the nail. It may be associated with pigment deposition in the periungual skin (Hutchinson’s sign) (picture 3 and picture 4) . (See "Longitudinal melanonychia".)

●Junctional nevus – A junctional nevus is composed of nests of melanocytes at the dermal-epidermal border. It appears as a painless dark spot in the nail bed or matrix. (See "Acquired melanocytic nevi (moles)", section on 'Cell of origin and classification'.)

●Splinter hemorrhages – Splinter hemorrhages can be seen with psoriasis or be associated with infectious endocarditis (picture 5). (See "Clinical manifestations and evaluation of adults with suspected left-sided native valve endocarditis", section on 'Clinical manifestations'.)

●Subungual keratoacanthoma – This tumor of the fingers and toes typically presents rapidly with pain, swelling, and inflammation. (See "Keratoacanthoma: Epidemiology, risk factors, and diagnosis", section on 'Clinical variants'.)

●Subungual epithelioma – This low grade malignancy is diagnosed by histologic exam.

●Subungual glomus tumor – A rare benign neoplasm arising from the glomus body and mainly found under the nail, on the fingertip or in the foot, subungual glomus tumors appear as red, purple, or blue lesions under the nail plate and may cause paroxysmal pain, cold sensitivity, and tenderness (picture 6A-B). (See "Overview of nail disorders", section on 'Glomus tumor'.)

TREPHINATION

Preparation

Patient counseling/informed consent — The child or adult with subungual hematoma is typically anxious and in significant pain. The patient and caregivers should receive an explanation of the problem and the planned approach. Anxiety usually recedes once the child's pain is adequately controlled. A child life specialist or other personnel may help with distracting the child during the procedure.

In general, the benefit of any of the trephination procedures outweighs the risk. The adverse effects of the technique should be disclosed prior to the initiation of the procedure based on the planned approach including [5]:

●Oozing of blood from the site of trephination

●Pain caused by pressure against or contact with the nail bed during the procedure

●Discoloration of the nail lasting up to four weeks

●Potential loss of the nail despite trephination, which is related to the primary injury and not the procedure

●Potential for clotting to plug the nail hole, leading to reaccumulation of blood

●Secondary infection of the nail bed and deeper structures (rare)

Materials — The clinician should assemble all equipment prior to the procedure:

●Infectious material precautions: latex-free gloves, eye protection, surgical mask

●25 gauge or smaller (eg, 27 gauge) needle and 3 to 5 mL syringe for lidocaine injection (if digital nerve block is planned)

●1 percent lidocaine without epinephrine or 0.25 percent bupivacaine (if digital nerve block is planned) (see 'Analgesia and sedation' below and "Subcutaneous infiltration of local anesthetics")

●Topical antiseptic (eg, povidone-iodine solution)

●Sterile gauze

●Trephination device (any one of the following depending upon chosen technique):

•Electrocautery: Electrocautery device or carbon laser [6,7]

•Aspiration: Insulin syringe needle (29 gauge) [8]

•Mesoscission device (eg, PathFormer) (picture 7) [9]

•Boring: Double bevel 23 gauge or single bevel 18 gauge needle [5,10]

Analgesia and sedation — As long as the clinician takes great care not to contact the nail bed during the procedure or to apply excessive pressure to the nail, nail trephination is typically painless because there are no nerve endings in the nail plate, and the hematoma provides a layer of separation from the nail bed which protects it from injury (figure 3).

However, any pressure may be exquisitely painful in some patients, especially those with concomitant distal phalanx fractures. A digital nerve block may be useful for analgesia in patients with associated distal phalanx fractures or nail matrix (plate) injuries requiring manipulation beyond simple trephination. Otherwise, trephination is a brief procedure and often brings instant pain relief, thus obviating the need for a digital nerve block. (See "Subcutaneous infiltration of local anesthetics" and "Digital nerve block", section on 'Fingers'.)

Rarely, anxiety may be great enough to warrant mild procedural sedation (eg, oral or intranasal midazolam), especially in young children. (See "Procedural sedation in children: Approach".)

Procedure — Subungual hematomas with an intact nail fold are treated with nail trephination [11,12]. Nail removal is only performed when concern exists that a nail matrix (plate) laceration has occurred (figure 1), or in the setting of an avulsion injury in which subungual sutures are necessary to repair the fingertip or toe tip. (See 'Nail removal' above.)

We suggest that patients with simple subungual hematomas undergo trephination by methods that avoid significant compression of the nail against the nail bed, such as cautery using an electrocautery device or carbon laser, aspiration with an insulin syringe needle (distal nail subungual hematomas only), or a mesoscission device rather than by boring through the nail with a needle. No studies have compared the benefits or risks of the different methods for trephination of subungual hematomas.

The clinician should not use a heated paper clip as a cautery device because it requires an open flame to heat the material. In addition, many paper clips are now made of metals (eg, aluminum) that are difficult to heat sufficiently to successfully penetrate the nail [5]. In contrast, electrocautery devices are widely available and effective.

●In selected patients, perform a digital block or sedation. (See "Digital nerve block" and "Procedural sedation in children: Approach" and "Procedural sedation in adults in the emergency department: General considerations, preparation, monitoring, and mitigating complications".)

●Restrain the extremity and digit. One approach is for the person performing the procedure to sit on the stretcher next to the patient's head and hold the hand and finger with the nondominant hand while obscuring the patient's view of the procedure. In some cases, additional personnel may be needed to hold the patient.

●Clean the nail with povidone iodine swabs using sterile technique. Isopropyl alcohol is highly flammable and should be avoided if electrocautery is used.

●Puncture the nail with a hot metal wire (eg, an electrocautery device [6]) or a carbon dioxide laser (figure 3) [7]. Press the device against the nail in the center of the hematoma while avoiding the lunula and its associated nail matrix. Avoid contact with the nail bed by controlling downward pressure and withdrawing as soon as blood drainage occurs. In some patients, the blood may spurt from the nail under high pressure. The hole should be large enough (3 to 4 mm) for continued drainage, which may occur for 24 to 36 hours after the injury.

●Alternatively, trephination can occur using one of the following methods:

•Insert an insulin syringe needle (29 gauge) underneath the nail at the distal hyponychium (figure 1) and advance it proximally and parallel to the nail plate with gentle suction on the syringe until the hematoma begins to drain [8]. Apply light pressure to the nail to complete evacuation. This method works especially well for subungual hematomas of the second through fifth toe tips.

•Using a mesoscission device (eg, PathFormer), bore multiple holes in the nail over the hematoma (picture 7). This device uses electrical resistance to determine depth of mechanical boring, thus avoiding inadvertent puncture of the nail bed [9].

•Twirl a needle while applying gentle pressure until blood is expressed through the hole [10]. If a small bore needle (eg, 23 gauge) is used, multiple holes should be placed to reduce the chance of plugging and hematoma reaccumulation. If a large bore needle (eg, 18 gauge) is used, a single 3 to 4 mm hole should suffice [5].

●Cover the puncture site with a sterile gauze dressing while the wound continues to drain.

In patients with simple subungual hematomas, the majority of patients will have an acceptable outcome with trephination alone, and poor outcome cannot be predicted by features such as hematoma size or the presence of a fracture [1]. (See 'Complications' below.)

PROPHYLACTIC ANTIBIOTICS — The use of prophylactic antibiotics for patients with a subungual hematoma varies depending upon several patient and injury factors:

●Subungual hematoma and no fracture – For patients with simple subungual hematomas and intact nail folds without a distal phalanx fracture, we suggest no prophylactic antibiotics regardless of whether trephination is performed or not. The use of prophylactic antibiotics does not appear to improve outcomes in these patients although evidence is limited. As an example, in an observational study of 47 patients with subungual hematomas who underwent simple trephination, no infections occurred, regardless of hematoma size or presence of distal phalanx fracture [13]. None of these patients received prophylactic antibiotics.

●Subungual hematoma and associated fracture – Patients with a distal phalanx fracture and a subungual hematoma have an open fracture. The approach to prophylactic antibiotics in these patients is discussed in detail separately (see "Distal phalanx fractures", section on 'Prophylactic antibiotics'):

•Tuft fracture – Tuft fractures are the most common fracture seen in a patient with a subungual hematoma and an intact nail fold. For healthy patients with a subungual hematoma and a tuft fracture, we do not suggest prophylactic antibiotics. Evidence for this recommendation is limited to one small trial of 193 adults with open distal phalanx fractures (tuft fractures were most common); infection rates were similar in patients receiving antibiotics compared with placebo [14]. However, the sample size in this study is insufficient to exclude a possible benefit. Thus, prophylactic antibiotics (eg, first-generation cephalosporin for seven days) are a reasonable option.  

•High-risk patients – For high-risk patients (eg, patient with diabetes mellitus or other immunocompromise) and any open distal phalanx fractures, prophylactic antibiotics are indicated.

•Salter-Harris fracture (Seymour fracture) – Children with hematomas that are associated with Salter Harris fractures of the distal phalanx (Seymour fracture) are at an increased risk of complications, including infection. Prophylactic antibiotics and referral to a hand specialist are warranted. However, these fractures are uncommon in patients with a subungual hematoma and an intact nail fold.

TETANUS PROPHYLAXIS — All patients with subungual hematomas should have their tetanus immunization status assessed. Tetanus prophylaxis should be provided as needed (table 1).(See "Tetanus".)

COMPLICATIONS — The potential complications of a subungual hematoma should be discussed with the patient and his or her caregivers. They include the possibility of onycholysis (ie, separation of the nail plate from the nail bed), nail deformity, nail loss, and infection. Complications are more likely to occur when care is delayed [15].

Evidence is limited but suggests that most patients report excellent or very good outcomes after simple trephination with no residual deformities in about two-thirds of patients [16]. Poor outcomes are rare. There appears to be no correlation between outcome and size of the hematoma or the presence of fracture or infection.

FOLLOW-UP CARE — After trephination, the clinician should instruct the patient and caregivers to keep the affected digit clean and dry. There is no need to soak the affected digit because this treatment may lead to fibrin clot breakdown and allow the introduction of bacteria into a previously sterile space [10].

Patients and caregivers should be instructed to return for reevaluation for any of the following reasons:

●Reaccumulation of the hematoma with pain

●Signs of infection (warmth, redness, excessive swelling, fever)

Patients who have subungual hematomas in association with a distal phalanx fracture should apply ice and elevate the digit during the first 24 to 48 hours to reduce soft tissue swelling and oral analgesia (eg, ibuprofen 10 mg/kg, maximum dose: 800 mg).

Nondisplaced distal phalanx fractures should be splinted with the DIP joint in extension for three to four weeks. Immobilization past four weeks may lead to excessive joint stiffness and some degree of loss of function. (See "Distal phalanx fractures", section on 'Management'.)

Salter-Harris, displaced, or intraarticular distal phalanx fractures warrant consultation with a hand or orthopedic surgeon at the initial evaluation. (See "Distal phalanx fractures", section on 'Indications for surgical referral'.)

Rarely, chronic subungual hematomas may be the result of child abuse [17]. When this is suspected, prompt involvement of an experienced child protection team (eg, social worker, nurse, physician with more extensive experience in the management of child abuse), if available, is indicated. In many parts of the world (including the United States, United Kingdom, and Australia), mandatory reporting of suspected cases of child abuse to appropriate governmental authorities is required. (See "Child abuse: Social and medicolegal issues", section on 'Reporting suspected abuse' and "Physical child abuse: Diagnostic evaluation and management" and "Child abuse: Social and medicolegal issues".)

SUMMARY AND RECOMMENDATIONS

●Terminology – Subungual hematomas (blood under the fingernail or toenail) may be simple (ie, the nail and nail fold are intact (picture 1)) or accompanied by significant injuries to the nail fold and digit (eg, fingertip avulsion, Salter-Harris fracture, mallet finger) (figure 1). Trephination is placing one or more holes in the nail to permit drainage of blood. (See 'Definitions' above and 'Anatomy' above.)

●Evaluation – The involved digit should have a complete neurovascular exam and specific assessment of the extensor tendon for evidence of tendon disruption at the distal interphalangeal (DIP) joint (mallet finger) (picture 2). The digit should be inspected for evidence of nail fold disruption, deformity, or avulsion. We obtain radiographs in all patients with large subungual hematomas because associated fractures are common, especially with subungual hematomas that occupy >50 percent of the nail plate. (See 'Evaluation' above.)

●Trephination

•Indications – Perform trephination for subungual hematomas that are acute (less than 24 to 48 hours old), not associated with Salter-Harris or displaced fractures, not spontaneously draining, associated with intact nail folds, and painful. After 48 hours, most subungual hematomas have clotted, and trephination is typically not effective. (See 'Trephination' above.)

•Large hematoma or underlying fracture – In patients with large subungual hematomas or underlying nondisplaced fractures and intact nail folds, we suggest trephination alone rather than performing nail removal and nail bed repair. The evidence supporting trephination alone is presented elsewhere. (See 'Nail removal' above and "Evaluation and management of fingertip injuries", section on 'Choice of procedure'.)

•Techniques – In a patient with a simple, painful subungual hematoma, we suggest trephination by methods that avoid significant compression of the nail against the nail bed rather than by boring through the nail with a needle, which increases pain (Grade 2C). Methods that avoid compression include the following (see 'Procedure' above):

-Cautery using an electrocautery device or carbon laser (figure 3) (do not use a heated paper clip as a cautery device)

-Aspiration with an insulin syringe needle (distal nail subungual hematomas only) (figure 1)

-Nail puncture with a mesoscission device (picture 8 and picture 7)

●Nail removal – Nail removal and nail bed laceration repair should be performed when a nail laceration threatens the preservation of the nail or digit (eg, nail fold injury with marked laceration of the nail bed, typically in association with a fingertip or toe avulsion). Indications for nail removal and management of nail bed lacerations are discussed in detail elsewhere. (See "Evaluation and management of fingertip injuries", section on 'Choice of procedure'.)

●Indications for hand surgery consultation – Patients with infected wounds, extensive nail bed injury, and displaced or intra-articular fractures should be evaluated by a hand surgeon. Subungual hematomas associated with Salter-Harris fractures (Seymour fractures) also warrant hand surgery evaluation. (See 'Subspecialty consultation or referral' above.)

●Prophylactic antibiotics – The use of prophylactic antibiotics for patients with a subungual hematoma varies depending upon several patient and injury factors (see 'Prophylactic antibiotics' above):

•In a patient with simple subungual hematomas and intact nail folds without a distal phalanx fracture (regardless of whether trephination is performed), we suggest to not administer prophylactic antibiotics (Grade 2C).

•In a patient with a distal phalanx fracture (ie, Tuft fracture) and a subungual hematoma who has no comorbidities, we suggest to not administer prophylactic antibiotics (Grade 2C). However, this is technically an open fracture; thus, prophylactic antibiotics are a reasonable option in a patient with comorbidities (eg, diabetes mellitus or other immunocompromise).

•Prophylactic antibiotics and referral are also warranted for children with subungual hematomas associated with Salter-Harris fractures (Seymour fractures) as this is considered an open fracture.

●Tetanus prophylaxis – All patients with subungual hematomas should have their tetanus immunization status assessed, and prophylaxis should be provided as needed (table 1). (See "Tetanus".)

●Follow-up care – After trephination, the patient should be instructed to keep the affected digit clean and dry; soaking is not needed. Nondisplaced distal phalanx fractures should be splinted with the DIP joint in extension for three to four weeks. (See 'Follow-up care' above.)