The internal iliac veins are short trunks, with no values, which begin superior to the greater sciatic foramen.

They are formed by the union of the anterior and posterior trunks, which receive tributaries corresponding to the branches of the internal iliac artery (with the exception of the iliolumbar and umbilical arteries); superior gluteal, internal pudendal, obturator, lateral sacral, middle rectal and vesical veins in both sexes, plus the uterine and vaginal veins in females 

They ascend postero-medially, slightly medial to the internal iliac arteries, to terminate anterior to the sacro-iliac joints by uniting with the external iliac veins to form the common iliac veins.