When Christine Knopp's son Brendan got a deep cut on his face, the ER doctor offered the option of a plastic surgeon for the stitches.
She said, "He was bleeding from his head, so I wanted to do what was right by him."
The surgeon's bill was $2,900. Christine had assumed her insurance would cover the surgeon. Not so.
"We were pretty shocked. We had no idea that that was going to become our responsibility," she said.
The problem was that, while the hospital was in the family's insurance network, the plastic surgeon who stitched up Brendan was not. Consumer Reports says one of the most common causes of medical sticker shock is going out-of-network.
"A PPO plan might say that it will pay 60 to 80 percent of out-of-network care," explained Nancy Metcalf with Consumer Reports. "That does not mean it will pay 60 to 80 percent of the actual bill, though. It means it will pay 60 to 80 percent of what the insurance company thinks the test or treatment ought to cost."
Consumer Reports found lots of examples of patients being hit with astronomical bills, including one woman who was charged $480,000 for back surgery.
Metcalf advised, "Bottom line, stay in your network. If you must go out-of-network, research ahead of time what your insurance company will pay."
Also research what the test or procedure should cost. Two services -- healthcarebluebook.com and fairhealthconsumer.org -- let you search the cost of medical services by zip code. Sometimes you can use this information to negotiate with the non-network provider you want to use.
And if like Christine you get a big bill, don't just complain to the insurance company. Enlist your employer and your state insurance department to help resolve the matter.
Many health insurance websites have tools where you can determine whether doctors are in or out of network. Before you have procedures done out-of-network, you'll want to ask what your insurance plan will cover.