Can you have gastric bypass if you have systemic vasculitis?

Yes. This would not automatically preclude you from having surgery. However, like everything, severe disease may put you at higher risk for certain complications.

Related Questions

Can you still have a gastric bypass when you have systemic vasculitis (churg strauss syndrome)?

Probably. Vasculitis alone does not rule out the possibility of having gastric bypass surgery. However, severe symptoms may increase your risk of certain complications. High dose steriods for example may complicate wound healing.