Umbilical cord carries oxygenated, nutrient-rich blood to the fetus, and two arteries that carry deoxygenated, nutrient-depleted blood away. Occasionally, only two vessels (one vein and one artery) are present in the umbilical cord. This is sometimes related to fetal abnormalities, but it may also occur without accompanying problems. It is unusual for a vein to carry oxygenated blood and for arteries to carry deoxygenated blood (the only other examples being the pulmonary veins and arteries, connecting the lungs to the heart). However, this naming convention reflects the fact that the umbilical vein carries blood towards the fetus's heart, while the umbilical arteries
Renal vein Renal vein The renal veins are veins that drain the kidney. They connect the kidney to the inferior vena cava. They carry the blood filtered by the kidney. There is one vein per kidney, that divides into 4 divisions upon entering the kidney: Because the inferior vena cava is on the right half of the body, the left renal vein is generally the longer of the two. Because the inferior vena cava is not laterally symmetrical, the left renal vein often receives the following veins: This is in contrast to the right side of the body, where these veins drain