Varicose veins may develop because of pressure and stress; they likely appear on the legs because of too much standing or sitting. A job like standing and sitting for hours can make a person adapt to the disease. Excessive pressure on the legs or abdomen negatively impacts the valves inside your veins. These veins inside become weak and damaged, and the blood pool in the veins. When the blood pools inside the veins, it causes them to twist and swell and bulge from the skin, which results in bluish-red cords in the skin called varicose veins.