Of all the culprits that make it harder for Americans to afford and access health care, the sheer confusion many patients experience when trying to select an insurance plan or when faced with an expensive medical bill may be the most overlooked.

That’s according to a recent survey from research firm Perry Undem, which reveals the deep confusion Americans feel when receiving health care — confusion that could put them on the hook for higher costs.

US health care costs are dire enough as-is, and it’s easy to look at the data on US prices for common procedures compared to the prices in other countries, or to compare the out-of-pocket costs Americans typically must pay for medical services under their insurance plan compared to their peers elsewhere and see the issue. It’s the prices, stupid, as some of the country’s leading health care economists once described the problem.

And the prices are indeed a big part of the US health system’s shortcomings: Research has shown that people will skip necessary care if they have even a small cost to pay, and recent surveys find one in three Americans say they have postponed medical treatment in the last year due to the cost.

The Perry Undem survey, which polled nearly 2,700 Americans on behalf of the American Cancer Society’s Cancer Action Network, the Leukemia and Lymphoma Society, and RIP Medical Debt, also detected widespread struggles to afford health care. About 7 in 10 people say they have received a medical bill that they could not afford, it found, and more than 60 percent of Americans said they had made some kind of sacrifice — delaying care, skipping appointments, changing the food they buy at the grocery store, etc. — in order to afford health care in the past two years.

But new data, from Perry Undem and from the health policy think tank KFF, further indicates that Americans have a lot of misconceptions about how their health care and insurance benefits are supposed to work, and could find themselves exposed to higher costs as a result. About 40 percent of people said they were always or frequently unsure how much their medical services would cost after they received care, according to the Perry Undem survey; another 30 percent said they were uncertain about the costs at least some of the time. Nearly two-thirds of US patients said they were at least sometimes unsure how much their insurance plan would cover after being treated.

More than half of Americans said they were either always, frequently, or sometimes uncertain about whether they had been seen by an in-network provider when receiving medical care. If they were treated by an out-of-network doctor, most insurance plans will charge the patient more money out-of-pocket for those services.

Those front-end issues — seeing a doctor or receiving a service not covered by your insurance plan — can create big medical bills in the first place. But patients also often don’t know what to do when they receive an invoice they can’t afford.

Only 3 in 10 Americans said they had fought or appealed a medical bill they had received. The survey reveals wide disparities in who has actively worked to reduce their health care bills: Older Americans, people with a college education, and white Americans were roughly twice as likely to say they had contested a medical bill than young adults, people without a college education, or Black Americans.

Why are so few Americans fighting back against exorbitant medical costs, even though 70 percent of those who did said they were successful in reducing their balance and experts like investigative journalist Marshall Allen have pleaded with patients to “never pay the first bill”?

Once again, confusion is to blame: 23 percent of respondents said they didn’t know they could fight a bill, 19 percent said they didn’t know the steps to take, 17 percent said that the process was overwhelming, and another 12 percent said they were too busy to contest a bill. Many Americans are also ignorant of the financial assistance that may be available to them: Nearly half of the people surveyed were not aware of the programs run by hospitals or physician practices that are meant to help patients pay their share of their bills. Only one in four said they had actually asked for or been offered such assistance.

The findings of the Perry Undem survey — that patients are often overwhelmed by the complexity of the health care system and unaware of their options to reduce their own costs — are consistent with other recent studies. KFF’s Larry Levitt and Drew Altman recently wrote in JAMA Forum that complexity in US health care is “the enemy of access and affordability,” citing results from a KFF survey taken over the summer.

About 6 in 10 Americans said they had experienced a problem using their health insurance in the past year, according to KFF. People reported being unable to receive care, experiencing a decline in their health, and/or paying more than they expected for treatment as a result of those insurance problems. In findings similar to those of Perry Undem, the KFF survey found 60 percent of Americans didn’t know they can appeal a medical bill and three-quarters didn’t know which government agency to contact for help with insurance issues.

“Complexity is [an] underappreciated problem that hinders access and affordability and is … difficult to quantify,” Levitt and Altman wrote in their commentary. “The reality is that many people are hopelessly confused by how their insurance works,”

The confusion starts during open enrollment, as Levitt and Altman noted, when people enrolling in Medicare Advantage have more than 40 plans available to them, on average, and people who sign up for coverage on the Affordable Care Act’s marketplaces may have more than 100 to choose from. HR industry surveys have also found that people who enroll in health insurance through their job often feel uncertain about the selections they are making.

And it continues as people actually receive medical treatment and then receive a bill, as evidenced by these findings. People don’t know if their providers are in-network or that they can contest a bill, and they may end up paying more than they should as a result.

Congress and the states have attempted to take steps in recent years to reduce the confusion among patients. Insurers are supposed to provide accessible and up-to-date provider directories. The No Surprises Act sought to remove patients from any disputes over out-of-network emergency bills, leaving the insurer and hospital to sort out the costs. But enforcement remains inconsistent, Levitt and Altman noted.

These surveys suggest that Americans remain perplexed by the process of seeking out medical services and paying for treatment — and their health is suffering as a result.