system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
In case of IVC obstruction, the collateral which opens up are all except
assistant
The correct answer is  Superficial epigastric vein drains into the femoral vein&ileo lumbar vein drains into common iliac vein Ref: Gray's 39e/p10