There are two renal veins, a left and a right. They branch off of the inferior vena cava and drain deoxygenated blood from the kidneys. As it enters the kidneys, each vein separates into two parts. Each branch connects to a certain location. The posterior vein assists in draining the posterior section of the kidney, while the anterior assists the anterior part. These veins also are responsible for draining blood from the ureter, which moves urine away from the kidneys to the urinary bladder. These veins should not be confused with the renal aorta. Unlike veins, the renal aorta delivers oxygenated blood to the kidneys. To simplify, aorta carry blood to the kidneys while veins move the blood away. There are two main diseases often associated with renal veins. If a clot or a thrombus develops, a condition called renal vein thrombosis (RVT) results. Symptoms include a diminished flow of urine while urine volume stays consistent. Treatment would require either anticoagulants and/or clot-removing surgery. Another issue includes nutcracker syndrome (NCS), which involves the one of the renal veins becoming compressed between abdominal aorta and the superior mesenteric artery.