In case of IVC obstruction the collaterals which open up are all except
Superficial epigastric pain drains into great saphenous vein.Iliolumbar vein drains into internal iliac vein,so these two do not form collateral between SVC & IVC as both of them will be ultimately drained into IVC.All other choices form collaterals between SVC & IVC. Ref: Chapter 8. The Chest: Chest Wall, Pulmonary, and Cardiovascular Systems; The Breasts. In LeBlond R.F., Brown D.D., DeGowin R.L. (Eds),DeGowin's Diagnostic Examination, 9e.
Superior epigastric & inferior epigastric vein
Azygos & ascending lumbar vein
Superficial epigastric & iliolumbar vein
Lateral thoracic veins & preveebral vein