CASE

A 28-year-old female presents to the emergency department for a chief complaint of finger pain after getting her hand caught in her car door. She presents with pain and blueish discoloration to the proximal aspect of the right thumb fingernail. The finger otherwise appears atraumatic. She is able to range her finger fully but is complaining of severe discomfort at the nail. The nailbed appears intact, and there are no overlying lacerations.

DIAGNOSIS

Subungual hematoma

DISCUSSION

A subungual hematoma is a collection of blood under the nail, which usually results from simple trauma to the nailbed. Patients present with intense pain resulting from the hematoma causing increased pressure under the nail. Most patients experience dramatic relief of symptoms from trephination, a procedure that makes a small hole in the nail.

Subungual hematomas may also be accompanied by distal phalanx fractures, nail avulsion, or fingertip avulsions [1]. It is important to assess for these with your exam and have a low threshold to obtain radiographs to assess for distal tuft fractures, as these are commonly associated with subungual hematomas and may require more involved repair.

Indications for trephination are presence of a subungual hematoma that is acute (less than 48 hours). There are no absolute contraindications for trephination. It is important to note that electrocautery devices should not be used on patients with acrylic nails due to fire risk – the acrylic nail needs to be removed prior to trephination in these cases [2]. Subungual hematoma with associated avulsion of the nail, a displaced distal phalanx fracture, or a proximal fracture involving the germinal matrix may require a surgical consult for removal of the nail and nail bed repair [1].

 Trephination

Equipment Needed

• PPE: face mask, eye protection, gloves

• Digital block: 25-gauge needle, 3-ml syringe, 1% lidocaine, gauze

• Trephination: Electrocautery device or 18-gauge needle

 Procedural Steps

Note: This procedure can be performed using an electrocautery device or a simple 18-gauge needle.

• Cleanse with iodine solution (not flammable alcohol)

• Electrocautery: Use electrocautery device at a 90-degree angle to drill a hole into the center of the subungual hematoma.

• Needle: Use an 18-gauge needle at a 90-degree angle over the central aspect of the hematoma and spin the needle to effectively “drill” a hole through the nail.

• In a pinch, you can also use a paperclip – heat the paperclip until red hot, then touch at a 90-degree angle to the center of the hematoma to burn a hole through the nail.

Follow-up

Advise patients not to soak finger, as this can introduce bacteria. Post-procedure antibiotics are not currently recommended. If a distal tuft fracture present, place a finger splint and arrange follow up with hand surgery. Inform the patient that the subungual hematoma should advance with nail growth over the next few weeks. If not advancing, they should follow-up with dermatology due to possibility of melanoma or a nevus. [1]

 TAKE-AWAYS

• Subungual hematomas are usually caused by simple trauma to the nail

• Assess for commonly associated injuries such as distal tuft fracture with x-ray imaging

• Trephination is indicated for subungual hematomas less than 48 hours old

• Providers can use an electrocautery device, 18-gauge needle, or a heated paperclip for trephination

AUTHOR: Lindsey Brown, MD, is a current second-year resident at Brown Emergency Medicine

FACULTY REVIEWER: Michelle Myles, MD, is an attending physician at Rhode Island Hospital and Miriam Hospital

REFERENCES

1.     Pingel, Caleb. “Subungual Hematoma Drainage.” StatPearls [Internet]., U.S. National Library of Medicine, 25 July 2023, www.ncbi.nlm.nih.gov/books/NBK482508/#:~:text=Introduction,finger%20pinched%20in%20a%20doorway. Accessed 13 Feb. 2024. 

2.     Ostermayer, Daniel et al. “Subungual Hematoma.” WikEM, wikem.org/wiki/Subungual_hematoma. Accessed 13 Feb. 2024. 

3.     Kiel, John. “Subungual Hematoma Management.” Sports Medicine Review, 25 Sept. 2023, www.sportsmedreview.com/blog/subungual-hematoma-management/. Accessed 13 Feb. 2024. 

4.     Espana, Thalia M. “Here’s What You Should Do When You Bruise a Fingernail.” Glam, 27 Nov. 2022, www.glam.com/1113231/heres-what-you-should-do-when-you-bruise-a-fingernail/. Accessed 20 Feb. 2024.