iliolumbar vein iliolumbar vein the iliolumbar vein is the vena comitans of the iliolumbar artery. iliolumbar veinthe veins of the right half of the male pelvis. (iliolumbar vein visible at center right.)detailsdrains tocommon iliac vein artery = iliolumbar arteryidentifierslatinvena iliolumbalista98a12.3.10.003ta25023fma18902anatomical terminology the obturator nerve crosses superficial to it. a single vein is found more commonly than a double vein. it drains vertebral segments four and five. it is closely related to the ascending lumbar vein.