Subungual Hematoma

Subungual hematoma is a localized collection of blood beneath the nail plate caused by trauma to the nail matrix or nail bed, with disruption of subungual blood vessels. Common causes include crush injuries (door slamming on finger), blunt impact, sports trauma (runners, hikers with downhill running causing hallux subungual hematoma — runner's toe), and repetitive microtrauma. The accumulating blood under the rigid nail plate generates significant pressure causing intense throbbing pain.

Clinical features include severe throbbing pain immediately after trauma, red-purple-black discoloration beneath nail that progresses to dark brown-black over days to weeks, distortion or partial separation of nail plate (onycholysis), and possible nail loss. Associated injuries include nail bed laceration, distal phalanx fracture (10–25% of cases warrant radiographs), and deeper soft tissue injury.

Diagnosis is clinical; radiographs of the affected digit identify associated tuft fracture or distal phalanx fracture. Subungual melanoma must be considered if pigment persists or expands beyond hematoma resolution time, warranting biopsy. Treatment depends on hematoma size, pain, and associated injury. Painful hematomas <25–50% of nail surface are treated with trephination using heated paperclip, electrocautery, or 18-gauge needle to puncture nail plate and drain blood, providing immediate pressure relief. Large hematomas with nail plate disruption, nail bed laceration, or open fracture warrant nail plate removal and nail bed repair with absorbable sutures.