Aside from the relationship drama, Dr. Bailey treats a young mother struggling to deal with a life-threatening breast cancer diagnosis.
The latter is familiar territory for Walsh.
"My mom, she's a breast cancer survivor and because of that I had started getting mammograms once a year, starting at age 30," Walsh said in an interview with The ShowBuzz Wednesday. "Previous to that my doctors had said, 'You don't have to start until 40 and older,' so I would have never even thought about it. You know, it's not the most comfortable procedure but it really is the best thing we've got doing in terms of early detection."
According to Walsh, tonight's episode, which is dedicated to breast cancer awareness, is especially powerful. "It's so compelling mostly in that (the character) is so young, she's in her 20s. I think a lot of people just aren't aware how young you can be and be diagnosed with breast cancer. The message, it's just heart wrenching, but it is ultimately one of hope," she said.
Walsh, 39, began her career in Chicago theater. She appeared on shows such as "Mind of a Married Man" and "The Drew Carey Show" before landing the "Grey's" gig in 2005. The Arizona native watched her mother, Angela, battle cancer after she was diagnosed around age 60.
Her mom is healthy today and will be watching tonight. "She watches every Thursday but particularly this Thursday," Walsh said. "I'm so happy that she's here, she's a strong powerful force of nature and I'm glad she's with me today."
Producers saw the episode as an opportunity to recognize Breast Cancer Awareness month.
"We have such a big audience and it's a great opportunity to put story lines out there that are socially relevant and medically relevant," said Walsh. "Our show-runner Shonda Rhimes feels very passionate about it, as do many of us who have personally come in contact with the disease."