In case of IVC obstruction, the collateral which opens up are all except
Superficial epigastric vein drains into the femoral vein&ileo lumbar vein drains into common iliac vein Ref: Gray's 39e/p10
Superior epigastric & inferior epigastric vein
Azygos& ascending lumbar vein
Superficial epigastric & ileolumbar vein
Lateral thoracic veins & preveebral vein
General anatomy