Surprise medical bills can be sprung on patients when hospitals use doctors or ambulances outside of a patient's healthcare network. Economist Jon Gruber joined Boston Public Radio on Thursday to talk about limited health insurance consequences and to take calls from our listeners.

"We all know when we sign up for our private health insurance plan that we're dealing with a limited network," Gruber said. "There's a set of doctors covered by your plan and if you can't see other doctors in what's called an HMO, or if you can see other doctors but have to pay more which is called the PPO, most of us are in plans like that today," he said.

An unintended consequence of limited network private health insurance plans can occur in times of emergency, Gruber said.

"When you're unconscious and go to the ER and an anesthesiologist comes in to check on you, no one is checking if that guy is in your network," he said. "If he's not, then you suddenly have to pay a lot more. So this is clearly a problematic situation."

Jonathan Gruber is Ford Professor of Economics at MIT and worked on both the Massachusetts health-care reform and the Affordable Care Act.