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Internal iliac artery

The internal iliac artery (IIA), also known as the hypogastric artery, is a major branch of the common iliac artery. It arises at the level of the sacroiliac joint, opposite the lumbosacral disc (L5–S1), and descends into the pelvis where it divides into anterior and posterior divisions.

The IIA provides the primary blood supply to the pelvic organs, gluteal region, perineum, and medial thigh. It gives rise to numerous visceral and parietal branches, and it forms extensive collateral networks with abdominal, lumbar, and femoral arteries.

Branches

  • Anterior division:

    • Umbilical artery (superior vesical arteries)

    • Obturator artery

    • Inferior vesical artery (males) / vaginal artery (females)

    • Middle rectal artery

    • Internal pudendal artery

    • Inferior gluteal artery

    • Uterine artery (females)

  • Posterior division:

    • Iliolumbar artery

    • Lateral sacral arteries

    • Superior gluteal artery

Clinical relevance: The IIA is crucial in pelvic surgery, trauma, embolization procedures, uterine artery embolization, and tumor interventions. Variations in branching patterns are common and must be recognized on imaging and in surgery.

Synonyms

  • Hypogastric artery

  • Arteria iliaca interna

Function

  • Supplies pelvic viscera: bladder, rectum, uterus, prostate, vagina

  • Supplies muscles of gluteal region and pelvic wall

  • Provides blood to perineum and medial thigh via internal pudendal and obturator arteries

  • Forms collateral circulation with lumbar, femoral, and external iliac systems

MRI Appearance

T1-weighted images:

  • IIA lumen: signal void (black) due to flow

  • Surrounding pelvic fat: bright, aiding identification

T2-weighted images:

  • Normal lumen: signal void

  • Thrombus, dissection, or slow flow: hyperintense signal relative to vessel wall

STIR:

  • Suppresses pelvic fat, making the artery more conspicuous

  • Highlights perivascular edema, hematoma, or inflammation

T1 Fat-Suppressed Post-Gadolinium:

  • IIA enhances brightly and homogeneously

  • Filling defects indicate thrombosis, emboli, or dissection

  • Useful for identifying aneurysms and tumor encasement

MRA Pelvis with Gadolinium:

  • Provides high-resolution 3D mapping of the IIA and its branches

  • Demonstrates branching pattern, anatomic variants, stenosis, aneurysms, or collateral circulation

  • Critical in embolization planning (e.g., fibroid embolization, pelvic trauma, GI bleeding)

CT Appearance

Non-contrast CT:

  • Vessel appears as tubular soft-tissue density at pelvic brim and sacroiliac joint

  • Detects vascular calcifications, thrombosis, or large aneurysms

CT Post-Contrast:

  • Artery enhances brightly with opacified lumen

  • Shows relation to pelvic organs and adjacent pathology

  • Useful in detecting active bleeding in trauma or rupture of aneurysm

CTA (CT Angiography):

  • Gold standard for non-invasive pelvic vascular mapping

  • Multiplanar and 3D reconstructions define origin, anterior/posterior divisions, and visceral/parietal branches

  • Identifies arterial stenosis, occlusion, aneurysms, arteriovenous malformations, and variant anatomy

  • Essential in surgical planning, embolization, and trauma evaluation

CT VRT 3D image

internal iliac artery CT 3D VRT anatomy image

CT image

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MRI image

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