In the few years since that survey, little has changed.

One of the biggest problems is that there are no price guidelines. Doctors negotiate different rates with different insurance carriers, so you could easily be charged one amount for a procedure one year, and a different amount if you switch insurance carriers.

The system is a breeding ground for billing errors. And many of these errors go undetected.

"The biggest part of the problem is that people think the hospital or medical practice will take care of that," said Kenneth Hertz, senior consultant with the Medical Group Management Association in Colorado. "If the contract exists between the consumer and the insurance company, it's really (the consumer's) ... responsibility to make sure the bill is correct."

So how do you catch an error?

Start by reviewing the explanation of benefits statement from your insurance company, said Jennifer McLaurin, a health insurance broker with John Sipp & Associates in Chapel Hill, N.C. "You need it to keep track of your charges."

The statement includes the date of your doctor's visit, which services you had, how much you were charged, the negotiated rate or allowed amount and the amount for which you are responsible.

If the statement from the doctor's office doesn't match this information, find out why.

Also double-check:

• The date. Make sure it matches the day you saw the doctor. Some people have complained about being charged for treatments after they cancel or miss an appointment.

• The patient's name. You could be charged for a treatment given to a patient whose name is similar to yours.

• Your insurance coverage. Before you go to the doctor, know what your health insurance will pay for and what will be your financial responsibility.

  If you are planning to have elective surgery, ask your doctor's office to call your insurer to find out what is covered.

• Compare the tests and treatments you are billed for against those that were done. Keep your own list, especially if you are going to be in the hospital overnight. If you're unable to do this, ask a family member or friend to keep a daily record of your treatments.

  If your bill seems unusually high, request a copy of your medical records to see which treatments your doctor ordered. Here are some common billing errors that those records can help you spot:

• Incorrect basic charges: A hospital charges $3,000 for a visit that typically costs $2,000. Your explanation of benefits can help you spot such an error. Look at what's allowed; if there's a big discrepancy, ask if the billed price is correct.

• Upcoding: The doctor's note shows that he switched your medication from an expensive to a generic one, but you are charged for both.

• Unbundled or double charges: The hospital charges for tests and blood work that is included in the cost of a procedure. Again, the explanation of benefits statement can help with this.

• Keystroke slip: You are charged for 22 units of blood instead of two.

• Canceled work: An expensive procedure was canceled, but you are still charged.

• Operating-room time: You're charged for 3.5 hours in the operating room, when the anesthesiologist's record shows that the surgery took only 2.5 hours.

Also, be on the lookout for fraudulent charges and signs of identity theft.

The National Health Care Anti-Fraud Association estimates that $60 billion, or 3 percent, of health-care payments are lost to outright fraud.

It sounds like a lot to keep track of, but you don't have to pull your hair out trying to monitor medical records.