Left renal vein

At a glance

English

Left renal vein

Latin (TA2)

Vena renalis sinistra

System

Vein

Region

Trunk

Side

Single, on the midline

About the left renal vein

The left renal vein carries blood from the left kidney to the inferior vena cava. Because the cava lies to the right of the midline, the left vein has much further to travel than the right, roughly three times its length, and it picks up several extra tributaries along the way. It runs at about the level of the first or second lumbar vertebra.

It is formed in the hilum of the kidney from several large veins that emerge from the renal sinus, lying in front of the renal pelvis and usually in front of the renal artery. Within the kidney the venous tree is not segmental in the way the arteries are; the intrarenal veins connect freely with one another. Leaving the hilum, the vein runs medially across the front of the left psoas and the left crus of the diaphragm. It then crosses the front of the abdominal aorta, just below the origin of the superior mesenteric artery, and opens into the left side of the inferior vena cava. In front of it lie the pancreas and the splenic vein.

On its way it receives the left suprarenal vein from above, the left inferior phrenic vein, often a lumbar vein (usually the second), and a small branch from the ureter. It is also commonly linked to the hemi-azygos or ascending lumbar system. On the right these vessels drain to the cava itself, which is one reason the two sides differ so much.

Normally each kidney has a single renal vein, though multiple renal veins occur. In some people the left vein passes behind the aorta rather than in front (a retroaortic vein), or splits into two channels that encircle it (a circumaortic collar). These variants matter to surgeons operating on the aorta and to anyone placing a vena cava filter. Where the vein passes between the aorta and the superior mesenteric artery it can be squeezed, causing the so-called nutcracker phenomenon, with flank pain and blood in the urine. Its length also makes the left kidney the usual choice for living donation.

Course and drainage

Begins at

Formed at the hilum of the left kidney by the union of veins emerging from the renal sinus.

Drains into

Crosses in front of the aorta, just below the origin of the superior mesenteric artery, to open into the left side of the inferior vena cava at about L1-L2.

Drains

Drains the left kidney, and via its tributaries the left suprarenal gland, part of the diaphragm, the upper ureter and part of the posterior abdominal wall.