In her monologue pre-recorded for Tuesday's show DeGeneres, 63, revealed that de Rossi, 48, told her around 7:30 p.m., "I'm not feeling well. I want to go to bed."
"And it was like 8 o'clock and that's early," she said before jokingly adding, "I'm not used to going to bed that early. We go to bed around 8:30."
The comedian said she took sleep medicine so that she could fall asleep at the same time as her wife, but she was abruptly woken up.
Ari and Louise Ellen DeGeneres and Portia de Rossi
"I look over and Portia is not in bed next to me," DeGeneres recalled. "I get out of bed and I find Portia on the floor on all fours. And I'm like, 'Baby are you okay?' And she says, 'Yeah, I'm okay.' And I said, 'Well you're okay if you're playing Twister by yourself, but you're not okay. You're on the floor.'"
The talk show host then drove de Rossi to the E.R. where she was admitted.
For more on Portia de Rossi's hospitalization, listen below to the episode of PEOPLE Every Day.
Due to the ongoing COVID-19 pandemic, DeGeneres wasn't able to stay with the actress.
"That's upsetting to me. They sent me home and I'm crying," she admitted, joking, "Because someone was chopping onions at the nurse's station."
DeGeneres also said de Rossi's pain was so severe that she offered to exchange tickets to The Ellen DeGeneres Show for more pain medication, which didn't work because "that's the rules."
"I am happy to report Portia is feeling much better now. She's home. She came home late yesterday," she added.
The comedian snuck in one more joke as she said, "Not all of her, she left her appendix at the hospital. I'm going to auction off the appendix for charity. I'm kidding, it's gonna go on eBay."
A source confirmed to PEOPLE on Monday that Portia was "rushed" to the hospital and that she was "in a lot of pain," a source tells PEOPLE.
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"It was appendicitis and she had surgery," the source revealed.
Appendicitis is a common condition in which the lining of the appendix is blocked and becomes inflamed, according to the Mayo Clinic. It causes intense pain, and if not treated quickly — typically with surgery to remove the appendix — the organ can burst.