After an extended absence from Gaffney, Lenox finally returned in Chicago Med season 12, episode 6, and her return could not have come at a better time. Things have been quite tumultuous at Gaffney after Miranda pushed Goodwin out as hospital director. Her replacement, Malorie Sloane, has been making a string of changes that have impacted both the hospital staff and the patients, including stripping Archer of his title as interim ED chief and putting Ripley in charge.
While Gaffney has been going through some major growing pains, Lenox has been nowhere to be found. Her absence has been particularly noticeable given everything happening in the ED, but there's an explanation for why Chicago Med has kept her away, and it’s fair for fans to wonder where Lenox has been, given that our only update came in the first episode of season 12.
In the season 12 premiere, we learned that Lenox had taken a three-month sabbatical from Gaffney in order to head to Zurich to participate in a drug trial for Gerstmann-Sträussler-Scheinker (GSS) disease. During her conversation with Ripley, the show did not reveal how many weeks or months into her sabbatical she was, which was by design, as the show wanted to keep things ambiguous.
Due to her sabbatical, Lenox did not appear in the second, third, fourth, or fifth episodes of season 12, with her only appearance in the season coming in the closing moments of the Chicago Med premiere. In the premiere, Lenox made a brief appearance via video call with Ripley, which was used to give fans the update on her whereabouts.

Sarah Ramos missed several Chicago Med season 12 episodes due to maternity leave
While the show wrote Ramos out of the series by having Lenox take some time away from Gaffney in order to enroll in a drug trial, the storyline was not one the writers just randomly decided to explore. In fact, it was quite the opposite.
The reason the writers introduced the storyline that saw Lenox taking a three-month sabbatical was to accommodate Ramos’s maternity leave. Ramos announced her pregnancy in early May, sharing the exciting news that she and husband Matt Spicer were expecting their first child together.
"Surprise! If you’re not surprised I’m pregnant, act like it!" Ramos wrote in her Instagram post announcing her pregnancy just weeks before the Chicago Med season 11 finale.
Given the timing of her pregnancy announcement, it was always expected that Ramos would miss several episodes of Chicago Med season 12. What was unclear at the time of her announcement was how many episodes she would miss and when those episodes would fall within the season.
While Ramos announced her pregnancy via Instagram, she kept the details about her child's birth private. However, the timing aligned nicely with the show's summer break, which prevented Ramos from missing a large number of episodes. Rather than being out for almost half the season, Ramos missed just four episodes and made a special appearance in the season 12 premiere to help explain Lenox's absence from the show rather than simply having that update occur off-screen.
