By: Jayne O'Donnell

Huge variations exist in the prices of some of the most common medical procedures across state lines, by according to a report major insurers released Wednesday, but some experts say the data is of little use to consumers who rarely know what they owe until the bills arrive.

The insurer-funded Health Care Cost Institute (HCCI) won't disclose which hospitals or doctors are the high-price culprits and instead are releasing how much states' average prices differ from national average.

California, for example, has average prices that are the same as the U.S. averages for dozens of the most common procedures, including pregnancy ultrasounds and cataract surgery. But Clearhealthcosts.com, which compiles prices in 10 metro areas using data from consumers, doctors and hospitals and its own staff members' research, finds a huge price disparity within a 100-mile radius of San Francisco for some procedures.