A vein doctor is called a vascular specialist or a vascular surgeon. The vascular system (or circulatory system) is comprised of all vessels that carry blood and lymph throughout the body. Simply put, the arteries (the arterial system) carry oxygenated blood from the heart to the other organs, while the veins (the venous system) carry deoxygenated blood back to the heart. The only veins that carry oxygenated blood are those in the pulmonary system, which carries blood to the lungs to be oxygenated before moving the blood to the rest of the body. The lymph vessels (the lymphatic system) carry lymphatic fluid throughout the body and plays a key role in the immune system.