A subungual hematoma is an organized collection of blood that develops locally, in the space between the nail bed and nail plate itself.
A subungual hematoma is a result of an acute injury to the fingernail or toenail. Therefore, it is expected to develop within a short period of time following the initial local trauma. Subungual hematomas constitute red, purple or black spots that are visible through the nail. They are commonly accompanied by a painful or throbbing sensation and edema of the injured tip of the toe or fingernail. As the nail continues to grow, hematomas move distally towards the tip of the nail.
Tumors that may develop underneath the nails of fingers or toes can be misdiagnosed as subungual hematomas. Their rate of development is significantly slower than that of a hematoma, they do not arise as a result of a traumatic injury and do not move towards the tip of the finger or toe as the nail grows.
Subungual hematomas are diagnosed by observation. Typical characteristics include a red, purple or black spot that is located underneath the fingernail or toenail and is visible through the nail itself. The patient is expected to report a forceful type of local injury that has occurred to the affected finger or toe. A plain radiograph may be useful to evaluate whether there has been a fracture of the toe or finger, but does it not confirm the diagnosis of a subungal hematoma .
The evaluation of a potential laceration of the nail bed can be done via surgical removal of the damaged nail for gross inspection of the nail bed. This is only carried out if the edges or nail margins are damaged.
Subungual hematomas are generally considered minor traumatic injuries and may subside without treatment. If the hematoma is small and the patient is asymptomatic, surgical drainage is usually not necessary. Trephination is the process of relieving the nail bed from the pressure of the hematoma. This may be carried out via various techniques: needle aspiration, cauterization or paper-clip method. Prior to decompression, a local nerve block is applied to the affected digit. Following the procedure, further therapeutic options consist of application of a splint, bandage and cold compress, depending on the type and severity of the injury and the possibility of a nail bed laceration.
Surgical decompression does not result to poor outcomes even when there is a coexistent fracture or when the hematoma is of a considerable size   . The sole contraindication is a fracture requiring surgical repair or the entrapment of the germinal matrix in the fracture  .
Even though treatment guidelines remain inconclusive, extensive subungual hematomas that affect from 25% to 50% of the nail bed, are usually treated with a partial or complete removal of the nail. This allows for a better inspection of the nail bed to detect a possible laceration of the nail bed. It has been estimated that up to 94% of the subungual hematomas are accompanied by a fracture to the distal phalanx may also be accompanied by a co-existing nail bed laceration . Such lacerations are should be surgically repaired.
Subungual hematomas may also require analgesics and application of antibiotic ointments.
Subungual hematomas are considered a relatively minor type of traumatic injury and may require surgical drainage. Following surgical drainage of the hematoma, patients are expected to be relieved from pain. The gap that remains beneath the nail plate will eventually grow out as the nail continues to grow.
A long-term complication of subungual hematomas is the possible nail bed laceration that might occur, which will require a partial or complete excision of the affected nail.
The traumatic event may lead to a deformed nail, either temporary or permanent. In general, nail deformities can occur independently of the efficacy of the therapy or the absence thereof. Another potential complication is the detachment of the nail as the growth process continues.
Subungual hematomas arise as a result of a forceful traumatic injury of the nail bed area. The extremities, and particularly the sections involving the fingers and toes feature a very rich vascular network. If there is an interruption to this blood supply as a consequence of a traumatic event, it can lead to local blood loss, eventually organizing into a hematoma.
Injuries that lead to a subungual hematoma are usually forceful, such as dropping a heavy object on the toe or crushing a fingernail beneath a heavy door .
The actual incidence of subungual hematomas has not been definitively calculated, due to the unwillingness of the patients to seek professional help; such injuries to the nail bed are usually viewed as non-emergent and, therefore, only a minority of the individuals affected by them will seek consult at the emergency department.
Subungual hematomas are commonly diagnosed as work-related injuries, accounting for nearly 15% of all accidents sustained at work. They are usually observed in people between the ages of 4 to 30, particularly in cases of professional athletes; over 75% of all injuries in the pediatric age group are fingertip injuries and 25% of the latter also include the nail bed .
A brief inspection of the anatomy of the nail is useful to fully understand the pathophysiological mechanisms that underlie a nail bed injury and, subsequently, a subungual hematoma  .
The nail is a tough structure that is composed of keratinized cells, whereas the nail bed is a type of soft tissue attached to the periosteum, composed of the germinal and sterile matrix. The perionychium comprises the nail bed and paronychia (the lateral nail folds), whereas the hyponychium is the regional junction between the nail bed and skin of the fingertip.
The perionychium is responsible for the formation of the nail. The majority of the keratinized material is produced by the germinal matrix, wherein the production of new cells pushes the already formed ones towards the fingertip and they flatten as they proceed towards the edges. The sterile matrix is closely attached to the dorsal periosteum and produces a small volume of the nail material, but its main function is to connect the nail to the nail bed.
Nails require from 70 to 160 days in order to reach their full length. Their process of regrowth after an acute injury is also characteristic: growth is minimal or even absent for 3 weeks and then is re-initiated at a rapid pace. This accounts for the small lumps that may appear as the nail reaches its full length, following a traumatic incident.
In order to prevent a subungual hematoma, any individual should protect themselves against a possible injury to the nail, either on the fingers or toes.
Professional athletes are advised to wear appropriate footwear that allows for enough space for the foot to move during strenuous exercise. Workers handling heavy objects should also take care not to drop them on their feet or injure their fingers when operating machines; footwear with steel toes are also a suitable alternative for the feet protection. Children should be monitored when opening and closing doors for the same reasons. Any individual lifting heavy objects should follow the guidelines for safe weight-lifting to prevent damage to the back and spine, as well as injuries to the fingers, toes and nails.
Subungual hematomas are regional collections of blood that accumulate between the nail plate and nail bed. They are induced by various types of injury to the nail bed and are attributed to leakage of blood from the vessels that are responsible for the abundant perfusion of the nail bed .
Subungual hematomas arise due to localized trauma to the nail bed and can develop in all digits of the upper and lower extremities. Those that are located on the toes are also commonly termed "runner's toes" or "jogger's toes", given the high frequency of their occurrence among athletes. Sudden and abrupt movements account for the frequent occurrence of subungual hematomas in cases of professional athletes, due to the excessive pressure exerted on the space between the nail bed and the nail itself. The traumatic injury leads to the formation of a hematoma, which causes significant pain and discomfort despite falling under the category of minor traumatic injuries .
Subungual hematomas may require surgical drainage in order to heal optimally. An accumulation of blood that is extensive enough to cover over half of the nail bed should be examined closely in order to eliminate the possibility of a nail bed laceration.
A subungual hematoma is a collection of blood that develops beneath the nail plate and specifically between the nail plate and the nail bed. Subungual hematomas develop as a result of acute and forceful injuries to the nails and can be located either on the fingers or toes. Both fingers and toes have a rich vascular supply. A severe traumatic injury can lead to damage sustained by the vessels and leakage of blood that is organized into a local blood collection, referred to as a hematoma. The pressure that the hematoma exerts on the nail bed causes both pain and discomfort.
Subungual hematomas may subside on their own, since they move distally as the nail grows. A complication that definitely requires professional medical help is nail bed laceration, which means that the nail bed is severely damaged and needs to be repaired surgically. Regardless of whether a person seeks medical treatment or not, the nail that has sustained a subungual hematoma may develop abnormally or may be deformed, either temporarily or permanently.
This type of hematoma has a typical appearance: a red, black or purple spot that is visible through the nail and grows with the nail towards the tip of the finger or toe. Patients report a throbbing sensation, discomfort and pain. Subungual hematomas are treated with decompression techniques, which involve the surgical drainage of the hematoma in order to relieve the pressure and alleviate symptoms of pain. When there is suspicion of a nail bed laceration, the nail needs to be partially or completely removed, in order to allow gross examination and treatment if present. A multitude of techniques is used to decompress a subungual hematoma. After the pressure is relieved, the patient may need to protect the area with splint and bandage application.