Trephination of Subungual Hematoma One Week Post-Injury
Do not perform trephination on a subungual hematoma one week after injury—the procedure is only effective and indicated in the acute setting when the blood remains liquid under pressure.
Timing Is Critical for Trephination Success
Trephination must be performed acutely (within 24-48 hours) while the blood is still liquid and under pressure causing pain. 1, 2 After one week, the hematoma has already organized, clotted, and begun resorbing, making drainage technically impossible and clinically pointless.
The primary indication for trephination is relief of acute pain from pressure buildup beneath the nail plate. 1, 2 By one week post-injury, this acute pressure has resolved regardless of whether drainage was performed, as the blood has clotted and the pressure has equalized.
Studies demonstrating successful trephination outcomes specifically describe immediate or early intervention, with pain relief occurring within 8 hours of the procedure. 1 No evidence supports delayed trephination beyond the acute phase.
What to Do Instead at One Week
Reassure the patient that the nail will grow out normally over 4 months on average (range 2-6 months), carrying the dried hematoma with it. 2 This is the natural history regardless of whether acute trephination was performed.
Examine for complications that may have developed: nail bed laceration, nail plate avulsion, or signs of infection (erythema, warmth, purulent drainage, fever). 2 These would require different interventions than trephination.
If a distal phalanx fracture was present initially but not diagnosed, obtain radiographs now if there is persistent pain, deformity, or functional impairment. 2 However, this does not change the recommendation against late trephination.
Advise against nail removal or nail bed exploration at this stage unless there is clear evidence of infection, significant nail bed disruption requiring repair, or a displaced fracture fragment. 2 Simple observation is appropriate for uncomplicated cases.
Why Late Trephination Fails
After 48-72 hours, the subungual blood has clotted and organized into a solid mass that cannot be drained through a small trephination hole. 1, 3 Attempting to create drainage at this point will only damage the nail plate without achieving evacuation.
The coagulated hematoma is adherent to both the nail plate and nail bed, making it impossible to evacuate without removing the entire nail—a procedure that is unnecessary and more morbid than simply allowing natural nail growth. 2