splinter hemorrhage

**Definition/appearance:** Small (1–3 mm), linear, dark red to brown streaks running longitudinally in the nail bed, in the direction of the nail's growth. Red early (fresh blood), turning brown/black with time. They do not blanch with pressure and grow out with the nail.

**Pathophysiology:** Longitudinal rete ridges of the nail bed hold capillaries aligned parallel to the nail axis. Extravasation of blood from damaged capillaries pools in these grooves, producing the "splinter" shape. Mechanisms include: - Microemboli (septic or bland) lodging in distal capillaries - Immune-complex or vasculitic damage to small vessels - Microthrombi (e.g., antiphospholipid syndrome) - Direct mechanical trauma

**Clinical significance/associations:** - **Infective endocarditis (IE):** Classic board association, e.g., *S. aureus* in IV drug users (acute, tricuspid) or viridans streptococci on damaged valves (subacute). In the modified Duke criteria, splinter hemorrhages are generally considered a vascular/embolic phenomenon (and they are a nonspecific finding). Other peripheral stigmata of IE include: - Janeway lesions: painless, macular lesions on palms/soles, from septic emboli - Osler nodes: painful nodules on finger/toe pads, from immune complexes - Roth spots: retinal hemorrhages with pale centers - Petechiae and conjunctival hemorrhages - **Most common cause overall:** Trauma (especially in manual workers, often proximal-to-distal in the distal nail bed). Trauma-related lesions are typically in just 1–2 nails, in the distal nail. - **Other causes:** - Vasculitis (e.g., polyarteritis nodosa, granulomatosis with polyangiitis) - Antiphospholipid syndrome and SLE - Rheumatoid arthritis - Trichinellosis (*Trichinella spiralis*), with periorbital edema, myalgia, and eosinophilia - Psoriasis, which can cause nail changes, including pitting, onycholysis, and oil-drop spots - Fungal nail disease - Scurvy and other coagulopathies - Drugs, such as anticoagulants, tetracyclines, and chemotherapy - Chronic conditions such as renal disease, hypertension, and diabetes - Hematologic conditions

**High-yield exam pearls:** - Many splinter hemorrhages in a patient with fever and a new murmur should prompt IE evaluation. This means obtaining at least 3 sets of blood cultures before antibiotics, then an echocardiogram (TTE, then TEE if needed). - Their specificity is low. A single distal lesion in a healthy person is usually traumatic, and they are not diagnostic of IE. - Distinguish from other nail findings: - Subungual hematoma: larger and caused by acute trauma - Melanonychia: pigmented streak that does not result from blood - Terry nails: proximal two-thirds white, seen in cirrhosis - Muehrcke lines: paired white transverse bands, seen in hypoalbuminemia - Clubbing: seen in lung cancer, IE, and cyanotic heart disease - Koilonychia: spoon nails, seen in iron deficiency

**Management:** Treat the underlying cause. The lesions themselves need no specific treatment and resolve as the nail grows out (about 3–6 months for fingernails).