What Is the Left Renal Vein?

The left renal vein is one of two renal veins that are part of the circulatory system, carrying de-oxygenated blood away from the kidneys. The right renal vein drains the right kidney, and the left renal vein drains the left kidney. The left renal vein is often longer then the right.

Both the right and left renal arteries branch away from the inferior vena cava (IVC), also called the posterior vena cava, and is a large vein whose function is to carry de-oxygenated blood from the lower portion of the body to the heart's right atrium. The inferior vena cava lays behind the abdominal cavity, or belly region, and travels alongside the right of the vertebral column, which is also known as the spinal column or backbone. The lower right side of the back of the heart is where the inferior vena cava goes into the right atrium.

The kidney is a bean-shaped organ with its concave side having an area called the hilus or hilum, which is an entry and exit point for nerves, veins, arteries, and other structures. Ideally each kidney has a single renal vein, but having multiple renal veins is a common variation. The renal arteries split into two branches where they enter the kidney's hilum.

The anterior, or top, branch gets blood from the top of the kidney. The posterior, or bottom, branch receives blood form the lower part of the kidney. It's not unusual for both renal arteries to have an additional branch that gets blood from the ureter, which is a tube that carries urine from the kidney to the bladder.

The inferior vena cava is located on the right side of the body, making the left renal vein longer than the right. Due to the fact that the inferior vena cava isn't identical on both sides, the left renal vein often is attached to other veins such as the left suprarenal vein, the left inferior phrenic vein, the left second lumbar vein, and the left gonadal vein, which is the left ovarian vein in females and the left testicular vein in males. The right side counterparts to these veins empty straight into the inferior vena cava.

Renal vein thrombosis is an ailment that can affect either the right or left renal vein. It is marked by a thrombus, or blood clot, blocking the vein. Symptoms of renal vein thrombosis include blood in the urine and lowered urine output. Another renal vein ailment is the nutcracker syndrome, also known as renal entrapment syndrome, which results from the left renal vein being compressed. The symptoms of nutcracker syndrome are wide-ranging, making diagnosis difficult.