A subungual hematoma(The word subungual is derived from the Latin sub meaning beneath and unguis, meaning nail or claw) is a transient condition where blood and fluid collect underneath the fingernail, toenail, blood pools under the nail, giving a reddish, brownish, blueish, or grey/blackish discoloration. This is usually caused by a traumatic injury such as hitting the thumb with a hammer, a direct blow or a crush injury, getting a finger pinched in a doorway, stubbing a toe, nail avulsion, or finger-tip avulsions. Most subungual hematomas can be relieved with simple trephination, a procedure that involves making a small hole in the nail, and treatments using cyanoacrylate tissue adhesives.
Wounds, simple lacerations of the nail bed and/or matrix, stellate lacerations, avulsion of the nail bed, ungual matrix defect, nail-bed injuries associated with fractures of the distal phalanx, and associated fingertip injuries.
Esthetic and functional classification according to the summed results.
| Nail growth | 0 = without growth; 1 = partial growth with restraints; and 2 = normal growth. |
| Nail growth | 0 ≤ 50%; 1 = between 50 and 75%; and 2 ≥ 75% of the size of the nail on the opposite side. |
| Nail shape | 0 = significant deformity in the vertical plane; 1 = small deformity in the vertical plane; and 2 = without deformity. |
| Total score: 6 | The results were obtained through addition and classification of the scores as good (5–6), fair (3–4), and poor (<3). |
The complete nail structure is named the perionychium it’s composed of the nail fold, the paronychium (the dorsal skin of the fingertip), the hyponychium (the keratinized distal end of the nail bed which is in touch with the skin of the fingertip), nail bed (composed of the germinal and sterile matrices) and nail. The germinal matrix is found on the ventral floor of the proximal nail fold. It extends to the lunula, the crescent-shaped lighter portion of the nail. The sterile matrix is very vascularized and located on the ventral floor of the distal nail bed and adds layers of cells liable for attaching the nail to the nail bed.
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