Veins that swell or bulge with pools of blood, are varicose veins, developing when they fail to circulate the blood properly.
These visible and bulging veins, are more common in the legs and thighs.
Aching, cramping, itching, swelling, fatigue are some of the symptoms.
Family history, sedentary life, weight gain, veins abnormalities, constipation and straining, are possible causes for its development.
Sometimes, swollen veins, when associated with high levels of bilirubin, can indicate a liver disease (the liver is incapable of adequately removing bilirubin in a timely manner due to blockage of bile ducts, liver diseases such as cirrhosis, acute hepatitis, or inherited problems with bilirubin processing, especially liver cirrhosis).
Hyperbilirubinemia can be a sign of excessive destruction of red blood cells in body (hemolytic anemia, sickle cell disease).

Consult a physician!