Venous Drainage of the Pelvis
The veins of the pelvis drain deoxygenated blood and return it to the heart. There are three major vessels involved in the venous drainage of the pelvis – the external iliac vein, internal iliac vein and common iliac vein (these correspond the major pelvic arteries).
In this article, we shall look at the anatomy of the pelvic veins – their anatomical course, tributaries, and clinical correlations.
Note: The ovarian/testicular vessels drain directly into the abdominal veins; into the inferior vena cava on the right and the renal vein on the left.
External Iliac Vein
The external iliac vein is a continuation of the femoral vein (the major vessel draining the lower limb), arising when the femoral vein crosses underneath the inguinal ligament. It ascends along the medial aspect of the external iliac artery, before joining with the internal iliac vein to form the common iliac vein.
During its short course, the external iliac vein receives the inferior epigastric and deep circumflex iliac veins.
Internal Iliac Vein
The internal iliac vein is responsible the majority of pelvic venous drainage, and receives numerous tributaries from veins that drain the pelvic region. It is formed near the greater sciatic foramen, ascending anteriorly to the sacroiliac joint, before combining with the external iliac vein to form the common iliac vein.
With the exception of the iliolumbar vein (which drains into the common iliac), the tributaries of the internal iliac vein correspond with the branches of the internal iliac artery. It receives venous blood from the:
- Superior and inferior gluteal veins – drains the buttock and upper thigh.
- Internal pudendal vein – drains the reproductive organs and part of the rectum (via the inferior rectal vein).
- Obturator vein
- Lateral sacral veins – drains part of the sacrum.
- Middle rectal vein – drains the bladder, prostate (in males only), and part of the rectum.
- Vesical veins – drains the urinary bladder via the vesical venous plexus.
- Uterine and vaginal veins – drain the female reproductive organs via the vaginal and uterine venous plexuses.
Common Iliac Vein
The common iliac vein is formed at the upper margin of the pubic symphysis by the union of the external and internal iliac veins. It receives two additional tributaries:
- Iliolumbar vein – drains the L4 and L5 vertebrae, and the iliopsoas muscle.
- Middle sacral veins – drain part of the sacrum.
The left and right common iliac veins combine at L5 to become the inferior vena cava, which empties into the inferior aspect of the right atrium.
Clinical Relevance – Pelvic Congestion Syndrome
The veins in the pelvis, particularly the ovarian veins in women, are prone to valve failure that may cause them to become dilated and tortuous (similar to varicose veins of the leg). This can cause intense pain within the pelvis, known as pelvic congestion syndrome. The pelvis contains too many structures to successfully dissect out a vein, and so pelvic venous embolisation is performed instead.
Using a venous catheter a guide wire is fed through, a contrast dye is used and affected vessels are embolised (blocked) with various substances, such as metal coils. Due to the rich venous anastomoses in the pelvis, one smaller vein can be tied off without compromising venous return.