First, call the doctor. This could be as simple as a miscoding.
There is a standard of diagnostic codes that is common to all insurance companies and it is huge. The last time I saw one it was probably nine inches thick with small print. There are literally tens of thousands of codes. If by any chance the billing company picked up an incorrect code - and that doesn't happen often but it does happen - the insurance company would have no way of knowing that the right tests were done but that there was an error in the diagnosis coding.
If the coding is correct, you still can ask your doctor to submit an explanation as to why he thought the tests in question were appropriate.
If that doesn't do the trick, then yes, you will be obligated to pay. It may not have been your fault but it wasn't the labs fault either and they are entitled to be paid for the work they did. You can argue the point with the doctor, but the bottom line is that you have the ultimate responsibility for all medical payments.
It's impossible to say with certainty whether there is a malpractice claim (assuming that the wrong tests were indeed done) but generally to support a malpractice claim you have to be able to show that the treatment fell below the expected standard of care AND that the patient suffered damages that are directly attributable to the treatment falling below standard. Bad outcome does not always mean malpractice.
