Watch 'Chicago Med's April Collapse in Pain in Episode 100 (VIDEO)

Meredith Jacobs

The last of the three current One Chicago shows celebrates a milestone on Monday, and one of Chicago Med's own is checking in to the ED.

TV Insider has an exclusive sneak peek at what leads to April (Yaya DaCosta) becoming one of her hospital's patients in the NBC drama's 100th episode.

April's going about her job when she grabs herself in pain significant enough to bring her to her knees. Those around her, including Will (Nick Gehlfuss) and Doris, quickly hurry to her side.

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The cake was created by 'Med's special effects make-up technician Dina Cimarusti.

Also in this episode, Hannah (Jessy Schram) returns to work after her time in rehab for her addiction. Watch the clip above to see who's not exactly pleased to see her back at the hospital — and who's ready to leap to her defense.

In "The Ghosts of the Past," Manning (Torrey DeVitto) and Charles (Oliver Platt) assist in a complicated case helping a four-year-old who is no stranger to the ED. Meanwhile, Crockett (Dominic Rains) and Ethan (Brian Tee) tend to a police officer who has a mysterious gunshot wound in his abdomen. Plus, relationships are tested when secrets are revealed.

Hannah Will Chicago Med Episode 100

(Elizabeth Sisson/NBC)

But in happier news, as the promo reveals, Maggie (Marlyne Barrett) and Ben (Charles Malik Whitfield) are getting married.

Chicago Med, Wednesdays, 8/7c, NBC