But while Trina definitely made her mark by launching an official complaint against new doctor Archie Hudson, viewers were left wondering where they'd seen the actress before.
Well, it turns out Trina - played by Donnaleigh Bailey - previously starred as Michelle Corrigan in BBC soap Doctors.
The 36-year-old also had a part in Casualty's spin-off series Holby City all the way back in 2004 as she played Debbie Allen.
Not only that, but Donnaleigh joined the Coronation Street cast as PC Jess Heywood more recently between October 2017 and July 2018.
"Where Have I seen that patient Trina before? #casualty," wrote one fan on Twitter.
Another said: "Is that Michelle the nurse from Doctors playing Trina? #Casualty"
"It’s Donnaleigh Bailey, loved her in #Doctors #Casualty," penned a third.
And Trina wasn't the only new character who caught viewers' attention, as Andrew Paul - who played officer Dave Quinnan in The Bill for 13 years - also showed up at the hospital.
"Loved seeing Andrew paul In casualty tonight #bringbackthebill," noticed one soap fan.
While another added: "@BBCCasualty OMG The Bill’s Dave Quinnan is in Casualty! #Casualty"
Familiar faces aside, things got emotional on the BBC drama last night when Duffy told Charlie she has been diagnosed with vascular dementia.
The nurse [Cathy Shipton] became emotional as she was forced to admit her diagnosis to her boss.
Tearing up, she said: "As my line manager it's only fair you know why I was late for work.
"I was seeing a neurologist, he thinks I'm in the early stages of vascular dementia.
"A few months ago I had a couple of falls, I didn't know why and my GP arranged some tests which were clear.
"Then I started experiencing some problems with my mood and my memory, and my behaviour. I forgot your birthday.
"I had some more tests, then an MRI scan and this morning the neurologist gave me his assessment."
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