Credit: Video Still

This preview of Grey's Anatomy Season 9, Episode 20: "She's Killing Me" (April 4) from Canada's CTV leaves us even more concerned about our favorite docs than even the already stressful American promo.

In this preview, Meredith tells Bailey, "I wanna know if I'm going to get Alzheimer's." Then we see Bailey say, "You have tested positive..." Cut to Derek telling Mer, "Even if you get the disease it's decades away," and Mer replying, "It might not be." Um, we don't like the sound of that.

Meanwhile, the docs appear to find several patients have developed the same infection. That's not good. Or, in Owen's words: "This is going to be a nightmare."

Here's the official synopsis of the episode:

Upon receiving some unsettling news, Meredith and Derek take preventative steps for their children's future; a group of Syrian doctors arrive at Grey Sloan Memorial Hospital for a crash course in basic surgical skills that they plan to apply in the field; and April decides to come clean to Matthew regarding the truth about her virginity. Meanwhile, multiple pre-op patients develop infections, causing one doctor to wonder if she is at fault.

Check out the preview!

Credit: YouTube Photo: Grey's Anatomy Season 9, Episode 20 Canadian Promo: A Nightmare

For more Grey’s spoilers, click here.

Catch the next new episode of Grey’s Anatomy on Thursday, April 4, 2013, at 9 p.m. ET/PT on ABC.

Rebecca Martin is an editor at Wetpaint Entertainment. Follow her on Twitter @BeccaDMartin.