Internal iliac vein

At a glance

English

Internal iliac vein

Latin (TA2)

Vena iliaca interna

System

Vein

Region

Trunk

Side

Paired, left and right

About the internal iliac vein

The internal iliac vein, once also called the hypogastric vein, is the main venous trunk of the pelvis. It collects blood from the pelvic walls and viscera, the buttock, the perineum, and the sacrum and coccyx, and carries it to the common iliac vein. It is a short, broad vessel, roughly three centimetres long.

It is formed just above the greater sciatic foramen, where several tributaries come together. From there it runs upwards, backwards and towards the midline, keeping behind its artery and a little medial to it, and ends anterior to the sacroiliac joint, where it meets the external iliac vein and the common iliac vein begins. Its relation to the artery is not fixed: on both sides, but especially the right, it often lies lateral to the artery as well. It lies on the obturator nerve, piriformis and the sacral plexus.

Unlike its artery, it has no fixed branching pattern, though its tributaries cover matching territories. From outside the pelvis it receives the superior and inferior gluteal veins, the internal pudendal vein and the obturator vein. From the front of the sacrum come the lateral sacral veins. From the venous plexuses around the pelvic organs it receives the middle rectal and vesical veins, among others. These plexuses communicate freely with one another and with the vertebral venous plexuses.

This rich network makes the internal iliac vein an important bypass. If a clot blocks the external iliac system, blood from the femoral vein can reach the heart through gluteal and obturator connections into the internal iliac vein. Conversely, injury to its tributaries during pelvic surgery can seriously impair venous drainage and leave one or both legs swollen. Its thin-walled tributaries also bleed heavily in pelvic fractures and are a hazard during operations deep in the pelvis.

Course and drainage

Begins at

Formed above the greater sciatic foramen by the union of several pelvic and gluteal tributaries.

Drains into

Ascends to meet the external iliac vein anterior to the sacroiliac joint; the common iliac vein starts there.

Drains

Drains the pelvic walls and organs, buttock, perineum, sacrum and coccyx.