LOS ANGELES - On a massive sound stage at Hollywood's Raleigh Studios, a woman is dying of ovarian cancer. One doctor wants to treat her traditionally, by removing her uterus and ovaries. Another wants the patient to participate in a clinical trial that might preserve her ability to have children, but could have serious side effects.

On a different day, an obstetrician is conflicted about whether to deliver a premature baby she believes was conceived solely because the umbilical-cord blood could save the family's older, dying child. Another doctor struggles to do what's right when his teenage patient - who has HIV but doesn't know it - confides that he plans to have sex for the first time.

Bioethical questions like these come up weekly on ABC's "Private Practice," the "Grey's Anatomy" spin-off that begins its second season Wednesday.

"We're telling stories ... that will provide a lot of moral debate among our doctors and maybe debate at home when you watch," said series creator Shonda Rhimes.

The issues they face cause plenty of drama for the doctors at the Oceanside Wellness Group, where Kate Walsh's character, Addison Montgomery, came to work after leaving "Grey's" Seattle Grace Hospital.

"They're all viable conflicts ... grounded in these medical stories," Walsh said. "It's topical but not so procedural that it's not a Shonda Rhimes show. You still have all the great dialogue and characters and stories and romance."

Like "Grey's Anatomy," "Private Practice" features an ensemble cast of doctors whose personal lives are often far messier than their professional ones. They have affairs with one another and struggle with love as they overcome tough medical challenges and the financial realities of keeping their medical co-op alive.

The bioethical issues raised are based on real medical cases and community concerns, said researcher and writer Elizabeth Klaviter.

"We look at the things that have ourselves and our family members and friends buzzing - the issues that people are talking about in terms of right or wrong and the laws, ethics and social morays that are put on us in terms of how we conduct ourselves," said Klaviter, who also researches cases for "Grey's Anatomy."

"Doctors disagree," she said. "We're looking for cases where there are different courses of action or treatment."

This season, the doctors at Oceanside Wellness will have to decide what rights prostitutes have to medical care and whether to treat a sex offender at their child-friendly practice. They also engage in an abortion debate that surprised actor Tim Daly, who plays Dr. Pete Wilder.

"I never thought we'd be doing something like that on Disney," which owns ABC, he said. "It was just these characters discussing their opinions and they didn't agree and they were passionate about it, just like in the real world."

Daly and his cast mates credit Rhimes and the show's writers for using the forum of a prime-time drama to inspire viewers to consider current bioethical issues.

"If you can make anybody think in this day and age, and entertain them at the same time, that's a dream come true," said KaDee Strickland, who plays Dr. Charlotte King, a physician at a rival hospital.

Making bioethics a theme of the show is "seductive," Walsh said, because it deepens the characters while raising important issues for viewers to ponder. Though she said it was a risk for her to leave "Grey's," she feels she landed in a good place.

"It was a risk, but it wasn't like sex-without-a-condom risk. It was an offer I couldn't refuse," she said. "I'm hugely grateful that it did really well last fall... It's really a testament to Shonda and her gift for being able to tap into the culture and the big collective consciousness of what people really relate to."

History proves that viewers respond to medical shows: "We may never end up in a courtroom or never end up arrested, but sooner or later everybody's going to come through the doors of a doctor's office," Rhimes said. Exploring bioethics adds a new dimension to the already-beloved genre.

"It's something more and more doctors are facing these days," Rhimes said. "It's just a very different way of looking at medicine that I don't think we normally think about - the ethics of what you're doing."