Varicose Veins
Dilated, tortuous superficial veins caused by incompetent venous valves that let blood reflux downward and pool under gravity, raising venous pressure until the skin itself begins to fail.
First principles
Veins normally rely on one-way valves to defy gravity
Blood is normally returned to the heart against gravity by one-way valves in the deep and superficial veins working with the calf-muscle pump; each valve closes to prevent backward flow, or reflux, when the muscle relaxes. When valves fail (from congenital weakness, chronic vein wall stretching, raised intra-abdominal pressure in pregnancy or obesity, or previous DVT damaging the valve cusps), blood refluxes downward and pools in the superficial veins under gravity, causing them to dilate and become tortuous: varicose veins.
Educational content pending clinical review. Not medical advice.