Corpus: Common iliac Vein

The common iliac vein is a large, paired body vein that is formed on both sides by the confluence of the external iliac vein and the internal iliac vein.

The common iliac vein ascends cranially and medially and accompanies the common iliac artery. At the level of the 5th lumbar vertebra, the left and right blood vessels form the inferior vena cava. This location is also known as the venous bifurcation. As the vena cava is offset to the right of the midline, the left common iliac vein is slightly longer than the right vessel.

• iliolumbar vein

As the left common iliac vein is crossed by the right common iliac artery, a vena iliaca compression syndrome (May-Thurner syndrome) occasionally occurs.