Consumers are increasingly turning to the Web to compare medical fees as the economy and less generous health benefits squeeze household budgets.
But combing through often confusing and overlapping Web sites set up by doctors, hospitals, insurers and state officials can be daunting.
And even when patients think they know exactly what they'll be paying, unexpected fees can quickly inflate medical bills.
That's why doing the research is just the start. Patients should also ask plenty of questions to avoid surprise charges.
Rising health care insurance premiums, co-pays and deductibles, as well as the growing number of uninsured, are creating new demand for data on the cost of medical services.
Traditionally, the vast majority of insured patients had little incentive to shop around because their plans protected them from the brunt of health care costs.
Of the 170 million Americans with health insurance, only 8 million, less than 5 percent, are in high-deductible plans, which require patients to pay a couple thousand dollars or more out of pocket before insurance coverage kicks in.
But that figure is growing as employers look to rein in rising health care costs while still offering some health benefits.
Meanwhile, as unemployment rises, experts estimate that 50 million people lack health care coverage.
Patients with insurance can start their search on their insurers' Web site.
Aetna, UnitedHealth Group and Cigna provide cost and quality information for thousands of hospitals, doctors and clinics.
The sites allow users to compare, for example, the out-of-pocket cost of having a MRI scan at different locations. In many cases, going to specialized imaging centers will be cheaper than going to hospitals, which charge higher fees to support their considerable overhead costs.
Despite the availability of online pricing information, patients are still facing unexpected costs fees from clinics and doctor's offices owned by hospitals. The charges, known as "facility fees," can amount to hundreds of dollars and are often not covered by insurers.
Hospitals say the charges help pay for upkeep as they expand their operations.
Experts recommend patients ask in advance whether a doctor's office is affiliated with a hospital, and whether there are extra charges. Patients should also check with their insurer to see whether facility fees are covered. Cigna, for instance, covers the fees so long as the care is "medically necessary," and covered by the patient's plan.
Many doctors also are making it easier for uninsured patients to budget the cost of medical care. Aggregators of this information, such as pricedoc.com, also are springing up.