[quote=@Undying Curiosity]
[@KoL] hemodialysis is for kidney failure, not sure what that has to do with bone marrow.
[/quote]

Oh y yeah, I remembered that after I wrote it. What I wanted to say it's that she need to exchange her blood with someone else. It's not a completely different concept but still...

Anyway, the fact is that she can't produce new blood or eliminate the old one, so she needs to change her blood with someone.

Edit:

You know a lot about medical stuff, huh? This process seems kinda complicated, but Emilia could pull it for sure stone her specialty is transmuting blood. What I though she would do is actually transmute the donor's blood/ tissue to be compatible with her, which is partially plausible.