Subungual hematomas are common nail bed injuries caused by blunt or sharp trauma to the fingers or toes. Bleeding from the rich vascular nail bed results in increased pressure under the nail and can cause significant discomfort. Subungual hematoma drainage, also known as nail bed trephination, can be performed to relieve this discomfort.
Point-of-care ultrasonography is an emerging tool used to detect nail bed injury and distal phalanx fractures in patients with finger trauma. For more comprehensive information on the workup and investigation of nail bed injuries, please review this resource.
Subungual hematoma drainage is indicated in the presence of a painful subungual hematoma with the nail edges intact.
Subungual hematoma drainage does not usually require routine anesthesia. A digital block may be considered for pain control but is typically not necessary for the procedure itself.
The patient should be resting with the finger in a comfortable position on a supportive surface (see image below).
The clinician should sit in a comfortable position on the side of the injury.
Prepare the finger with povidone-iodine solution (Betadine). See the video below.
Using the preferred tool for nail penetration, make a hole at the base of the nail or in the center of the hematoma. This hole must be large enough for the hematoma to drain.
If using an 18-gauge needle, twirl the needle between the thumb and index finger with slight downward pressure until no resistance is felt and dark blood return is seen from the hole. See the video below.
If using a sterile cautery tool, activate cautery until the tip is hot. Apply the tool to the nail as with a heated paper clip.
Allow the hematoma to drain. Gentle squeezing at the tip of the finger may facilitate hematoma drainage.
Apply antibacterial ointment (eg, bacitracin) over the trephination site and dress the wound with gauze or an adhesive bandage. See the video below.
When appropriate, take a radiograph of the finger to rule out an underlying fracture that may require splinting.
Hematomas that are larger than 50% of the nail do not necessarily require nail removal and exploration.
The nail may fall off during the week following hematoma drainage but should regrow as long as the germinal matrix is intact.
Multiple holes may be necessary to facilitate adequate drainage.
If the heat of an electrocautery device is painful for the patient (which is not typical), an 18-gauge needle should instead be used for trephination.
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Cite this: Richard H. Sinert. Skill Checkup: Subungual Hematoma Drainage - Medscape - Oct 08, 2019.