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Topic

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Internal iliac vein

The internal iliac vein (IIV) is a major venous trunk of the pelvis that drains blood from the pelvic organs, gluteal region, and perineum. It begins near the upper margin of the greater sciatic foramen, formed by the convergence of the gluteal and pelvic venous tributaries, and ascends posterior to the internal iliac artery.

It unites with the external iliac vein at the level of the sacroiliac joint to form the common iliac vein, which ultimately drains into the inferior vena cava.

The IIV receives blood from numerous tributaries: superior and inferior gluteal veins, internal pudendal vein, obturator vein, lateral sacral veins, vesical veins, prostatic plexus (in males), uterine and vaginal veins (in females), rectal venous plexus, and iliolumbar vein.

Because of its extensive venous plexuses, the IIV plays an essential role in pelvic circulation, collateral drainage in venous obstruction, and tumor spread.

Synonyms

  • Hypogastric vein (historical term)

  • Vena iliaca interna

Function

  • Collects venous blood from pelvic organs (bladder, rectum, uterus, vagina, prostate)

  • Drains the gluteal region, obturator region, and perineum

  • Provides collateral venous pathways via pelvic venous plexuses

  • Important in venous return from pelvis to common iliac vein

MRI Appearance

T1-weighted images:

  • Internal iliac vein: linear hypointense lumen surrounded by intermediate pelvic fat

  • Tributaries can be followed when large or dilated

T2-weighted images:

  • Flowing blood: signal void

  • Thrombosis or sluggish flow: hyperintense or heterogeneous intraluminal signal

STIR:

  • Fat suppression improves vessel conspicuity against pelvic fat

  • Thrombophlebitis or perivascular edema: bright hyperintensity

T1 Fat-Suppressed Post-Gadolinium:

  • Enhances brightly and homogenously, outlining venous plexus tributaries

  • Useful in detecting thrombosis, tumor encasement, and varices

MRV (Magnetic Resonance Venography):

  • Normal signal: enhancing blood appears bright hyperintense

  • Thrombosed vein: appears hypointense, with filling defect

  • Depicts full pelvic venous anatomy, including tributaries and communications

  • Essential for pelvic congestion syndrome, venous mapping, and surgical planning

CT Appearance

Non-contrast CT:

  • Vein often indistinct unless enlarged

  • Appears as soft-tissue density posterior to internal iliac artery

CT Post-Contrast:

  • Enhances well, delineating main trunk and tributaries

  • Detects extrinsic compression, tumor invasion, or venous dilation

CTV (CT Venography):

  • Normal signal: venous lumen appears bright hyperdense

  • Thrombosis: intraluminal filling defect with or without expansion of vein

  • Excellent for 3D mapping of IIV tributaries and corona mortis connections

  • Critical for trauma, oncology, and preoperative pelvic vascular mapping

MRI image

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MRI image

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CT image

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CT image

internal iliac vein ct axial image

CT image

Internal iliac vein ct coronal