I would say that if she has a virus or another infection, they will postpone the surgery. Even with transplants, if the person is sick when they get the call, they will not do the transplants. Even though this is kind of reversed, I had just had my colon removed when the docs found out that I was in acute rejection with my new lungs. They would not treat me for the rejection because I had just had the surgery and if they put me on the high doses of steroids for it, it would have hindered my healing from the surgery. It is the same way with having and infection during a surgery. The infection could hinder her healing from the surgery, or worse, whatever infection or virus she may have, could spread.
I hope that she is well and that they can go ahead with the g-tube. Good luck to you and let us know what happens!