"It just got to the point where I could barely breathe," McKenna said.
She was transferred by ambulance to a larger Baylor Scott & White hospital for surgery. At each stop, the staff took her private insurance card. Yet a few weeks later, she was told much of her treatment was out-of-network. She owed more than $40,000.
"I remember crying. I was very upset," McKenna said.
McKenna is just one of over 600 people CBS News has heard from in our Medical Price Roulette series that highlights the financial gamble consumers face with medical care.
Insurance broker Lora Everist, who sold McKenna her insurance policy, said paying cash would have been cheaper.
"Nobody gave her the option to pay cash or self-pay," Everist said.
Everist said McKenna's insurance paid over $6,000 for the surgery. McKenna negotiated a few bills down, but Baylor Scott & White still wants $27,000 more.
"Because there is no guideline. There is no transparency. They can charge whatever they want," Everist said.
Baylor Scott & White responded, saying its facility charges are lower than other acute care hospitals in the region. But this case shows what they call an "opportunity for improvement," and they now say they'll be contacting McKenna to work toward solving her problem.
What should you do in an emergency?
There are a few things patients can do when faced with a medical emergency. First, find out now which hospitals are close to you that are in your network. Next, if it's not a life-threatening emergency, consider a cheaper walk-in or urgent care center. If you wind up in the emergency room, ask, or have someone with you ask, if the doctors treating you are in your network.