If you thought a lot went into creating every episode of

Dr. Arizona Robbins made a triumphant return to Grey Sloan Memorial Hospital this week, stopping by to do a groundbreaking surgery that reminded Dr. Miranda Bailey just how magical the OR can be. In the episode, titled Baby, Can I Hold You, Arizona performs the first-ever in utero vein of Galen surgery on a fetus, with the help of Dr. Jo Wilson and Dr. Amelia Shepherd.

The vein of Galen is essentially a blood vessel, which can malfunction and cause heart and lung issues, and if the baby doesnt receive surgery in time, it can be fatal. Its very rare, and surgery is usually done after the baby is born. But remarkably, ambitious doctors, including the one who inspired this story, Dr. Darren Orbach, are now attempting to work in utero. Though Arizonas procedure on a visually impaired pregnant woman, played by Aria Mia Loberti, is touted as the inaugural surgery on-screen, it has actually been done successfully a few times in real life.

When we wanted to bring [Arizona] back, we wanted to do something really cool, explains Dr. Michael Metzner, a producer and medical adviser on Greys Anatomy. Her character has so much history on this show of being a badass and pushing the envelope, and I think this medical story does just that.

To bring the surgery to life on-screen, Metzner and the Greys crew worked with the real doctors and hospitals involved in the experimental technique. Here, he breaks down how they did it.

EMILY ZEMLER: When an episode includes an experimental surgery, how involved are you in helping to shape how its written?

MICHAEL METZNER: Im in the writers room, so Im pitching stories. A lot of times, that will be Whats the theme of the episode? How do we create a medical story that pairs with it? Some of these stories are our stories with our own patients and things that weve gone through in training. I have a lot of fellow physicians call me all the time and say, Oh, my God, Michael, you have no idea what I just saw.

We also have a researcher who is not medically trained but is always scouring the headlines for new and cool things that are happening within medicine. So, its a team effort. Im the only physician who is in the writers room and is on set to work with all the actors and directors, and I also do all the postproduction. So, I get to actually see the idea be created, and help to create it, and then actually make it happen, and then work in the back end as well.

Miranda Bailey (Chandra Wilson) and Dr. Arizona Robbins (Jessica Capshaw) presenting the innovative surgery.

EZ: Has a vein of Galen surgery been done in utero before?

MM: They were looking at this research back in the 90s, but all of the outcomes were really bad. All of the babies died. So, no ones touched it in a long time. It is not standard of care by any means, and right now its still experimental. But at this point, I believe five surgeries now have been done, and they have all been successful. The technology has come a pretty long way since the first time that these things were attempted.

EZ: How did you incorporate the real-life medical research and surgeries into the episode?

MM: Once we saw the headline about it, we reached out to Boston Childrens Hospital and Dr. Darren Orbach, who is the physician who helped to develop this new technique. We brought him on as a consultant and interviewed him many times to make sure that we were getting this as accurate as possible, just because its a very controversial thing. Its still in its experimental stage, so there are a lot of fetal surgeons who advocate against doing something like this because of the history of it. But now, there are these cases in small numbers that have been successful.

EZ: What did Dr. Orbach share that was helpful?

MM: For the FDA and IRB [Institutional Review Board] approvals, they had to make these phantom skulls with different possibilities of skull thickness where they actually practice putting needles through different thickness of skulls. That way, whoever the neuro-interventionalist is working on it will get the feel of what that would be like. It was actually what the real doctors practiced on. So, the prop skulls that we used in the episodes were the real ones from Boston Childrens and Brigham & Womens Hospital at Harvard. You can see them when Amelia is working in the skills lab with a needle.

EZ: Was it difficult to borrow something like that?

MM: We had to have the sign-off from the surgeon from two different hospitals, plus the family whose fetus was worked on. I was trying to coordinate all of that to make sure everyone was on the same page. And the images we used were the actual images from the surgery. So, what youre seeing in the background on our show is actually them doing the surgery in Boston, which is pretty cool. Thats all real.

EZ: Is it typical that Greys Anatomy would use real scans or images of a procedure in an episode?

MM: When a surgery has only been done a few times, thats the only thing we can use. Weve done it in the past. Some of the images from our partial heart transplant last season were from [a real] OR. Later this season, we have a device were showing off, and we flew the inventor in from Sweden and put him and his wife in a scene. We have a lot of footage of all the different surgical procedures we will use. But if it is something super-special like this, and we can get the physician and the family and the hospital to agree, then we will use it.

EZ: What were the challenges of bringing this surgery to life on-screen?

MM: I remember calling Dr. Orbach and saying, I need to know every single needle and every single piece of equipment, to the detail that you used. We actually reached out to those companies and got the specific things that they would use to make it as accurate as possible. Then, I worked with our video-playback person to cut up the visual representations of the surgery to what would match to the scenes of the story were trying to tell. I worked with the actors and the director to have them mimic whats going on in the surgery footage with their hands and with the actual equipment to marry the two.

EZ: Is it accurate that the mother would be awake for the surgery?

MM: For pregnant women, we try not to do anesthesia, so they would be completely awake. They have an epidural, so they dont feel anything. And they often put headphones or music on. She was lying on the table with a fake pregnancy belly. Depending on what were shooting, we can sometimes film separate scenes with the patient, but for this one I think she was there the entire time. She had breaks, but she was lying down on the OR table.

EZ: Did you have any special guests in the episode besides Jessica Capshaw?

MM: We flew Dr. Orbach in, and I put him in the surgery scene. So, the gentleman across from Amelia and Arizona is actually Dr. Orbach, who is holding the ultrasound. The coolest thing is that when its done, theres one shot where you can tell hes smiling under his mask, and it felt historic. We have this cool story, and then heres the man who was one of the inventors of the method in the scene.

Emily Zemler is a freelance writer and journalist based in London. She regularly contributes to the Los Angeles Times, Rolling Stone, PureWow, and TripSavvy, and is the author of two books. Follow her on Twitter @emilyzemler.

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How the 'Grey's Anatomy' Crew Works With Real-Life Doctors to Bring The Most Complicated Procedures to TV - Shondaland.com