This has happened to me.

It is very frustrating but one learns to be very careful if you have PPO insurance (preferred provider, where in network facilities are covered, but out of network may received less than 50% coverage.)

To find an in network gastroenterologist, usually you go to your insurance company's website. But then to find that the doctor has chosen an out of network facility (where often he is part owner) or anesthesiologist is infuriating. The surprise usually arrives only when you get the bill or notice of coverage from your insurance company.

Even though you may be paying thousands in annual health insurance premiums, this means you are only half covered and can end up paying over $1000 in uncovered charges.

So you learn to get a list of all firms who will be billing you and call your insurance company to be sure each is in network.

And by all means call the doctors office and scream about the out of network charges. Next time, find another doctor.