Credit: Video Still

Personal drama often outweighs medical stories on Grey's Anatomy, but it looks like the case on Season 9, Episode 13: "Bad Blood" will be very compelling.

In this sneak peek of the episode, Cristina (Sandra Oh) and intern Leah (Tessa Ferrer) have to treat a patient whose parents refuse to allow the docs to perform a life saving blood transfusion because of their religious beliefs.

That raises an interesting moral dilemma, and at the very end of the sneak peek it looks like Leah decides to take matters into her own hands — she steals a bag of blood. Will she really give her patient a blood transfusion without permission?

Credit: YouTube Photo: Grey's Anatomy Season 9, Episode 13 Sneak Peek: Why Can't Cristina Treat Her Patient? (VIDEO)

For more Grey’s spoilers, click here.

Catch the next new episode of Grey’s Anatomy on Thursday, January 31, 2013, at 9 p.m. ET/PT on ABC.