What are Splinter Hemorrhages?
Splinter Hemorrhages are tiny blood spots that appear underneath the nail. They look like very thin, vertical, reddish-brown lines—strikingly similar to a small wooden splinter stuck under the nail plate. They are caused by tiny blood vessels (capillaries) bleeding within the longitudinal grooves of the nail bed.
Clinical Presentation & Location
The location of the hemorrhage on the nail is a massive clue to its underlying cause.
Distal Hemorrhages (Near the tip)
- Usually located on the middle or tip third of the nail.
- Almost always caused by physical trauma.
- Very common in manual laborers or athletes.
- Will naturally grow out with the nail.
Proximal Hemorrhages (Near cuticle)
- Located closer to the lunula (the white half-moon).
- Highly suggestive of systemic disease.
- Warrants immediate medical investigation.
Systemic Red Flags
While trauma is the most common cause, splinter hemorrhages are famously taught in medical schools as a classic physical sign of severe systemic conditions, specifically involving the heart.
- Infective Endocarditis: An infection of the heart valves. Tiny blood clots (microemboli) travel from the heart and lodge in the small capillaries of the nail bed, causing them to burst.
- Vasculitis: Inflammation of the blood vessels, which weakens capillary walls causing them to leak.
- Psoriasis: Nail psoriasis often causes localized capillary damage resulting in these splinters, alongside pitting and onycholysis.
- Scleroderma & Lupus: Autoimmune connective tissue diseases that attack small blood vessels.
When to Seek Immediate Care
If you have splinter hemorrhages that appeared suddenly on multiple nails without any history of trauma, and you are experiencing a fever, fatigue, or a newly discovered heart murmur, you must seek emergency medical evaluation for infective endocarditis. If they are isolated to a single toe you recently stubbed, they are harmless and will grow out.