Venous Collateral Pathways

• Axillary or subclavian vein occlusion: Collateral flow through muscular and superficial veins of the shoulder, scapula, and chest wall into the ipsilateral internal jugular and intercostal veins, and the contralateral jugular or subclavian veins.
• Brachiocephalic vein occlusion: 1) Collateral flow through deep and superficial veins of the back, chest, and neck into the contralateral jugular, subclavian, and brachiocephalic veins. 2) Collateral flow through superficial chest wall veins such as the internal mammary and intercostal veins into the azygos (if right-sided occlusion) or hemiazygos (if left-sided) or into inferior epigastric veins.
• Superior vena cava occlusion above azygos vein: Collateral flow through the chest wall and intercostal veins into the azygos system.
• Superior vena cava occlusion below azygos vein: Collateral flow through retrograde flow in the azygos vein into the inferior vena cava.
• Superior vena cava occlusion above and below azygos vein: Collateral flow through chest wall and intercostal veins into the azygos and hemiazygos system into the inferior vena cava.
• Inferior vena cava occlusion below the renal veins: Collateral flow through ascending lumbar, paraspinal, gonadal, inferior epigastric, and abdominal wall veins.
• Inferior vena cava occlusion between renal and hepatic veins: Collateral flow through ascending lumbar, paraspinal, gonadal, inferior epigastric, and abdominal wall veins (as above) and azygos and hemiazygos veins (particularly for the renal veins)
• Inferior vena cava occlusion above hepatic veins: Collateral flow through ascending lumbar, paraspinal, gonadal, inferior epigastric, and abdominal wall veins, as well as azygos and hemiazygos veins (as above). In addition, gonadal and ureteric veins can also serve as collaterals.
• Right renal vein occlusion: Collateral flow through lumbar, ureteric and azygos veins.
• Left renal vein occlusion: Collateral flow through lumbar, hemiazygos , and left gonadal veins.
• Adrenal vein occlusion: Collateral flow through small retroperitoneal veins such as the renal capsular veins.
• Gonadal vein occlusion: Collateral flow through transpelvic, ascending lumbar, and internal iliac veins.
• Splenic vein occlusion: 1) Collateral flow through the short gastric veins into the left gastric vein. 2) Collateral flow through the omental vein to the gastroepiploic or superior mesenteric vein. Frequently submucosal collaterals prone to bleeding into the gastrointestinal tract.
• Central superior mesenteric artery occlusion: Collateral flow through mesenteric, paraduodenal, and marginal veins. Frequently submucosal collaterals prone to bleeding into the gastrointestinal tract.
• Portal vein occlusion: Collateral flow through network of small veins in the gastrohepatic ligament (cavernous transformation). Portal-to systemic varices.
• Main hepatic vein obstruction: Intrahepatic collateralization or collateral flow through capsular veins.
• External iliac and common femoral vein obstruction: 1) Collateral flow through profunda femoral veins to gluteal and other pelvic veins into the internal iliac veins. 2) Collateral flow through the ipsilateral abdominal wall veins and across the perineum to the contralateral common femoral vein.
• Internal iliac vein occlusion (unilateral): Collateral flow through contralateral internal iliac vein.
• Internal iliac vein occlusion (bilateral): Collateral flow through gonadal, ureteric, and the inferior mesenteric veins (via hemorrhoidal veins).
• Common iliac vein occlusion (unilateral): Retrograde flow through the ipsilateral internal iliac vein, across the pelvis through collaterals, into the contralateral internal iliac vein.
• Common iliac vein occlusion (bilateral): Identical to infrarenal inferior vena cava occlusion (see above).
• Common and external iliac vein occlusion: Collateral flow through pubic, inferior epigastric, and lumbar veins.

References

Kaufman JA and Lee MJ. Multiple chapters in Vascular and interventional radiology: The Requisites. Mosby 20004.