A splinter hemorrhage is a small area of bleeding that occurs beneath the nail plate, either on the fingernails or toenails. This bleeding originates from the tiny capillaries that run along the nail bed. The blood leaks from the damaged vessels and becomes trapped between the nail bed and the protective nail plate.
Visual Characteristics and Location
These marks are named “splinter” hemorrhages because of their distinct visual similarity to a small piece of wood lodged under the nail. They appear as thin, dark streaks that typically measure between one and three millimeters in length. These streaks run longitudinally, aligning parallel with the natural direction of nail growth.
The color changes of the mark can indicate its age, initially appearing bright red or purplish before oxidizing to a darker reddish-brown or black over a few days. The hemorrhage itself is fixed to the nail bed and does not move when pressing on the nail plate. As the nail grows outward, the streak will gradually move toward the tip and eventually disappear as the nail is trimmed.
Traumatic vs. Systemic Causes
Splinter hemorrhages result from one of two distinct causes: localized trauma or a systemic condition. Most commonly, these streaks are benign and result from direct physical injury to the nail apparatus. This can occur from events like accidentally hitting a finger with a hammer, stubbing a toe forcefully, or even from minor, repetitive actions such as aggressive manicures or engaging in certain sports.
Trauma causes the capillaries in the nail bed to rupture, leading to the localized bleeding. Hemorrhages caused by injury are usually confined to a single nail and tend to be located in the distal portion, closer to the free edge of the nail. They resolve naturally as the nail grows out and do not require specific medical intervention beyond managing any associated pain from the injury itself.
When splinter hemorrhages appear spontaneously (without preceding injury), they can indicate a systemic disease. The most commonly cited and serious systemic cause is infective endocarditis, which is an infection of the inner lining of the heart’s chambers and valves. In this condition, tiny fragments of infected material or blood clots, called microemboli, break off and travel through the bloodstream, lodging in the small vessels of the nail bed and causing the hemorrhage.
Systemic hemorrhages often differ from traumatic ones, frequently appearing on multiple nails and sometimes in the proximal area, closer to the cuticle. Other conditions that can cause this phenomenon include vasculitis, which is inflammation of the blood vessels, and certain connective tissue disorders like systemic lupus erythematosus (SLE). A doctor may also explore less common causes such as nail psoriasis or reactions to certain medications that affect blood clotting.
When to Seek Medical Evaluation
While a single splinter hemorrhage following a known injury is not a concern, certain indicators suggest the need for medical evaluation. Consult a physician if the marks appear spontaneously, meaning you cannot recall recent trauma to the affected finger or toe. The presence of multiple hemorrhages across several different nails significantly raises suspicion for an underlying systemic issue that needs investigation.
It is particularly important to seek prompt attention if the splinter hemorrhages are accompanied by other unexplained symptoms. These associated signs can include a persistent fever, sudden chills, unexplained fatigue, muscle aches, or shortness of breath. These symptoms, when paired with the hemorrhages, can be suggestive of infective endocarditis, a condition requiring immediate diagnosis and treatment.
During an evaluation, a doctor will conduct a physical examination and inquire about recent injuries or illnesses. If a systemic cause like endocarditis is suspected, diagnostic tests may be ordered, such as blood cultures to check for infection, a complete blood count, or an echocardiogram to visualize the heart’s function and valves. Seeking consultation is important when the hemorrhages appear without a clear traumatic cause.