Of the venous tributaries mentioned above, the lumbar veins are unique in their connections and deserve special attention. Not all of the lumbar veins drain directly into the inferior vena cava (Fig. 4.167):
The fifth lumbar vein generally drains into the iliolumbar vein, a tributary of the common iliac vein.
The third and fourth lumbar veins usually drain into the inferior vena cava.
The first and second lumbar veins may empty into the ascending lumbar veins.