"It gets really sticky, so we use a lot of Sterilube, which is just a fancy term for, like, K-Y Jelly. And so, that's all over," Donnell told TVGuide.com during a recent tour of the Chicago Med set. "There's a lot of blood and lube."
Check out the video above to get a behind-the-scenes look at key areas of the hospital, including the operating room and what's known as the "football."
Chicago Med airs Tuesdays at 9/8c on NBC.