NEW YORK (MainStreet) — On March 18, 2013, Health and Human Services (HHS) Secretary Kathleen Sebelius announced that an estimated 71 million Americans who had private health insurance had coverage for preventive health care, such as a mammogram or flu shot, in 2011 and 2012 as a result of the Affordable Care Act.

"No longer do Americans have to choose between paying for preventive care and groceries," Sebelius said.

Tell that to Nancy B. Irwin, a therapist and life coach, whose recent "free" physical cost her $600 as a result of having to pay for the work up and the follow-up appointment to interpret the results.

Or Adam C. Powell, who heads up Payer+Provider Syndicate, a consulting firm that helps solve operational problems for health insurance companies and hospitals. He got stuck with a $500 phlebotomy bill.

The problem is that preventive services, which don't require a copay or a deductible be met, and which are often roped in as part of a routine physical, include only a specific list of checks and screenings. These include questions from your doctor about aspirin use to prevent heart disease as well as high blood pressure and alcohol abuse screenings. Preventive care also includes coverage for certain vaccines, such as the flu shot. But go outside those bounds and complain about your arthritis or constipation, and you may get a bill for an office visit. Put another way, you may have to pay if the preventive consultation isn't the primary purpose of your visit or if your doctor bills you separately for the preventive service and the office visit.

And that's far from the only thing that can rack up a big bill from your free preventive care visit. If your doctor is an out-of-network provider, you may be charged a fee. In fact, you may have to foot the whole bill.

And brace yourself. The costs can add up if your free mammogram screening leads to diagnostic testing or your check up leads to blood tests that aren't covered under preventive care services.

Grandfathered plans are another problem. Coverage for preventive care is not required by law under these older plans.

--Written for MainStreet by S.Z. Berg, author of The Other Side of the Window, a medical mystery about the failure of the medical community