"Having done eight or nine hundred action movies, I hurt myself putting on a pair of leggings in my hotel room," the Underworld star quipped.
Beckinsale was in Las Vegas filming the movie Prisoner's Daughter when the incident occurred.
"I was doing a very intense emotional drama and not running up walls or anything," she said. "I was in my hotel room putting on a pair of leggings, and it felt like a sort of guitar string snapped and everything was horrible. I mean, worse than having a baby bad, bad. I couldn't walk, I couldn't lie down, I couldn't sit down. I couldn't do anything."
This proved to be a hurdle for paramedics who came to get Beckinsale to the hospital.
"Eventually an ambulance came and they sort of rolled out a sheet and picked me up in it like a, sort of, sausage, and put me on a gurney," she noted, laughing.
Beckinsale, who doesn't drink, was put on a lot of medication at the hospital.
"I really found out what kind of a drunk I am first, so did everyone else," she joked. "I'm not a 'Do you know who I am? Have you seen all my films?'-type, which is a huge relief because I'm really glad I'm not. But I am a 'Everybody's trying to steal my f**king ovaries.'"
Showing off the leggings she was wearing for the televised appearance, Beckinsale insisted, "I'm alright now!"
Earlier this month, Beckinsale opened up to ET about her daughter, Lily, following in her and her ex, Michael Sheen's, acting footsteps.
"I think it's really important to her to have her own thing and blaze her own trail and do her own stuff," Beckinsale told ET. "So as much as it's quite difficult not to kind of be poking into her business all the time, I really do respect that and I admire how much she wants to be independent from us."