Surprise medical bills spell big trouble for consumers, especially those who find themselves in an emergency room. Such “surprises” have surfaced as a major patient problem, but because of entrenched healthcare interests, a solution is not likely any time soon.

Here’s what happens. Patients arrive at the emergency room of a hospital that is in their insurer’s provider network. However, the physician who treats them is out of network.

Because ER docs are usually assured a steady stream of patients, many believe they don’t need to accept potentially lower fees from insurers in exchange for any new patients they might attract by belonging to a network. That’s not the case for other specialists who may rely on insurer networks for more business.

Whatever the reason, emergency room patients may be stuck with huge bills their insurance company may not cover, or it will pay less than if patients had used in-network doctors.

If you think this is unfair, it is.

A study by Yale researchers of more than 2 million emergency room visits across the country was just published in the New England Journal of Medicine. It found that out-of-network doctors treated 22 percent of the patients who visited emergency departments; the departments themselves were part of their insurers’ networks.

The average bill patients incurred was $623. The highest bill was more than $19,000. To put that number in perspective, this year the Federal Reserve reported that 46 percent of Americans were unable to pay a $400 expense without running up credit card debt or selling assets.

Not surprisingly, researchers found out-of-network ER doctors ended up getting paid a lot more than those who were part of a network. “The fact this type of price gouging has become routine operating procedure in so many emergency departments is shameful and appalling,” says Chuck Bell, programs director for Consumers Union.

A recent study in Texas by the Center for Public Policy Priorities shows how prevalent out-of-network ER doctors are. Using a 2013 report from the Texas Department of Insurance, the Center found that 45 percent of in-network hospitals in the state used by United Healthcare had no in-network ER doctors. Fifty-six percent of Humana’s hospitals had none. “Consumers would be astonished to see how poor the odds are of getting an in-network doctor in the emergency room.” Bell added.

The odds of getting redress are also low. Too many consumers don’t contest their bills. Only about 25 percent of those getting surprise bills do, Bell told me. Of those who do protest to their insurer, only half get their bill forgiven or reduced.

Surprise bills are a variation of what’s called balance billing, the gap between what insurance, including Medicare, pays and what a doctor charges. It’s been around for decades, but in the late 1980s, the outcry from Medicare beneficiaries became so loud that Congress did something about it.

For doctors who accept Medicare’s payment in full, there is no balance billing - called “excess charges” in Medicare speak. Doctors, including ER physicians who don’t accept that payment, can sock beneficiaries with excess charges. But Medicare limits what they can charge.

Beneficiaries can protect themselves from these excess charges should they use a doctor who doesn’t accept Medicare’s fee schedule by buying Medigap policies Plan F and Plan G. For those with Medicare Advantage plans, there’s no protection until the beneficiary reaches the plan’s out-of-pocket spending limit. After that, the doctor can’t balance bill separately.

There’s no similar help for those not on Medicare.

Many consumers are unaware that an out-of-network doctor is treating them.

The standard advice - to ask if your doctor is in the network - is silly when it comes to care in the ER. What patient having a heart attack is going to look up and say, “Hey doc, are you with Aetna?”

A few states – New York, California, Illinois, Connecticut, and Florida – hold patients harmless if they find themselves with a surprise bill or require outside arbitration to decide a case. But Bell says it will take an act of Congress to solve this problem. Public outrage will have to get much louder if that’s to happen.

Because chances are high you’ll find yourself with such a bill, think twice before you choose to go to the ER for a problem that can wait until you see your regular doctor.

Although Obamacare was supposed to cut down on emergency room use, that hasn’t happened. People are still going to ERs for less serious conditions, many being enticed by hospitals themselves that advertise their ER wait times on billboards.

Our healthcare system is all about making money. And balance billing, its causes and consequences, is another sorry example.

What is your experience with surprise billing? Write to Trudy at trudy.lieberman@gmail.com.