Common iliac vein
Vena iliaca communis
A short paired vein of the lower abdomen, formed anterior to the sacroiliac joint, that joins its partner to make the inferior vena cava.
At a glance
- English
- Common iliac vein
- Latin (TA2)
- Vena iliaca communis
- System
- Vein
- Region
- Trunk
- Side
- Paired, left and right
About the common iliac vein
Each common iliac vein carries blood from one lower limb and half of the pelvis up towards the inferior vena cava. It arises anterior to the sacroiliac joint, where the external iliac vein from the leg meets the internal iliac vein from the pelvis. The two common iliac veins then climb obliquely and unite opposite the body of L5, slightly right of the midline, to begin the inferior vena cava. Each travels alongside the common iliac artery of the same side.
Because the vena cava lies on the right, the two veins differ. The right vein is short and runs almost straight up, lying first behind and then to the outer side of its artery. The left vein is longer and more slanted; it passes medial to its own artery and then deep to the right common iliac artery to reach the point of union. Both receive the iliolumbar vein and sometimes lateral sacral veins, while the median sacral vein usually ends in the left one. In an uncommon variant the left vein continues up on the left of the aorta as far as the kidney, takes in the left renal vein, and only then passes across the front of the aorta to the vena cava.
The way the right common iliac artery crosses the left vein has clinical weight. Where the artery passes over it, the vein can be pressed against the body of the fifth lumbar vertebra, an arrangement known as May-Thurner syndrome or iliac vein compression. Constant arterial pulsation is thought to irritate the vein wall, so that fibrous tissue builds up inside it as spurs or webs. The narrowed vein may then cause lasting swelling of the left leg and favour deep vein thrombosis, which is why left-sided leg clots in young adults prompt imaging of this segment.
Together with the external and internal iliac veins, the common iliac veins form the main outflow of the lower limbs and pelvis.
Course and drainage
- Begins at
- Formed anterior to the sacroiliac joint by the union of the external and internal iliac veins.
- Drains into
- Meets its partner opposite L5, slightly right of the midline and deep to the right common iliac artery, creating the inferior vena cava.
- Drains
- Drains the lower limb and pelvis of its side, receiving the iliolumbar vein and, on the left, the median sacral vein.
Anthromica
See the common iliac vein where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
