A subungual hematoma occupying more than 50% of the nail bed should prompt evaluation for fracture of which structure?

• A. Distal Radius
• B. Metacarpal
• C. Underlying Phalanx
• D. Humerus

Answer: (C)

Subungual bleeding under the nail is a sign that the tip of the finger has been injured, and the nail bed sits directly on the distal phalanx. When the hematoma covers more than half of the nail bed, it strongly suggests a fracture of the distal phalanx, since damage to this bone beneath the nail bed often drives the bleeding that tracks under the nail. Fractures of the radius, metacarpal, or humerus are farther up the limb and don’t explain a large nail bed hematoma with localized fingertip tenderness. So, the structure to evaluate for fracture is the distal phalanx.