Bill Dunphy thought his colonoscopy would be free.
His insurance company told him it would be covered 100 percent, with no copayment from him and no charge against his deductible. The nation's year-old health care law requires most insurance plans to cover all costs for preventive care, including colon cancer screening.
So Dunphy had the procedure in April.
Then the bill arrived: $1,100.
Dunphy, a 61-year-old Phoenix business owner, paid it out of his own pocket because of what some prevention advocates call a loophole. His doctor removed two noncancerous polyps during the colonoscopy. So while Dunphy was sedated, his preventive screening turned into a diagnostic procedure. That allowed his insurance company to bill him.
Like many Americans, Dunphy has a high-deductible insurance plan. He hadn't spent his deductible yet. So, on top of his $400 monthly premium, he had to pay the bill.
"That's bait and switch," Dunphy said. "If it isn't fraud, it's immoral."
President Obama's health care overhaul encourages prevention by requiring most insurance plans to pay for preventive care. More than 22 million Medicare patients and many more Americans with private insurance have received one or more free, covered preventive services this year. From cancer screenings to flu shots, many services no longer cost patients money.
But there are confusing exceptions. As Dunphy found out, colonoscopies can go from free to pricey while the patient is under anesthesia.
Breast cancer screenings can cause confusion, too.
In Florida, business owner Dawn Thomas, 50, went for a screening mammogram. But she was told by hospital staff that her mammogram would be a diagnostic test -- not preventive screening -- because a previous mammogram had found something suspicious. (It turned out to be nothing.)
Knowing that change would cost her $700 and that her doctor had ordered a screening mammogram, Thomas stood her ground.
"Either I get a screening today, or I'm putting my clothes back on and I'm leaving," she remembers telling the hospital staff. It worked. Her mammogram was counted as preventive, and she got it for free.
"A lot of women are getting labeled with that diagnostic code and having to pay year after year for that," Thomas said. "It's a loophole so insurance companies don't have to pay for it."
How confused are doctors?
"Extremely," said Cheryl Gregg Fahrenholz, an Ohio consultant who works with physicians. It's common for doctors to deal with 200 different insurance plans. And some older plans are exempt.
Should insurance now pay for aspirin? Aspirin to prevent heart disease and stroke is one of the covered services for older patients. But it's unclear whether insurers are supposed to pay only for doctors to tell older patients about aspirin -- or whether they're supposed to pay for the aspirin itself, said Dr. Jason Spangler, chief medical officer for the nonpartisan Partnership for Prevention.
The greatest source of confusion is colonoscopies, a test for the nation's second-leading cancer killer. When a doctor screens and treats at the same time, the patient could get a surprise.
"It erodes a trust relationship the patients may have had with their doctors," said Dr. Joel Brill of the American Gastroenterological Association. "We get blamed. And it's not our fault."
Cindy Holtzman, an insurance agent in Marietta, Ga., tells clients to check with their insurance plans before a colonoscopy so they know what to expect. "You could wake up with a $2,000 bill because they find that little bitty polyp," she said.