This week on Grey's Anatomy, Meredith finally tells Derek about the miscarriage and is cleared to return to surgery, while perhaps Cristina should not have been, as she experiences PTSD at a really bad time - the worst possible time for a doctor, as a matter of fact.

In these sneak preview clips we've posted from "Shock to the System," the surgeons continue to struggle internally in the aftermath of the shooting. Callie and Arizona arguing over home decor may not be one of the bigger problems at stake, but they're at odds too ...

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Follow the jump for many more sneak peeks at this Thursday's episode, in which Mer has it out with Der, Mark wants to propose, and Bailey refuses to let Alex operate unless ...

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Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.