Kansans remain among the most vulnerable in the country to surprise medical bills — charges from outside an insurance network that the consumer only discovers after treatment.

A new research brief from the Kansas Health Institute points to studies suggesting the charges are common in Kansas. It’s part of a shrinking minority of states yet to pass laws reining in the practice.

Surprise medical bills happen when a patient gets care at an in-network hospital, clinic or doctor’s office, only to get hit with third-party, out-of-network bills for services such as anesthesia or lab tests.

Other times, medical emergencies land people in ambulances and emergency rooms where their insurance doesn’t help much.

In both scenarios, the surprise charges result from services where the patient had no choice between out-of-network and in-network options.

Figuring out how common this is isn’t easy. Pricing and billing practices are proprietary information and are largely hidden from the public’s view. There is no complete national data to turn to.

But researchers use a variety of insurance databases and other sources to gauge the situation as best they can.

The Health Care Cost Institute has built up one such trove. When it scoured more than 600,000 claims for people who sought in-network inpatient care in 37 states, Kansas came second only to Florida for the highest rate of out-of-network charges.

One in four patients in Kansas ended up with out-of-network services through an in-network hospital.

Researchers who dug into another database with 19 million claims from 40 states found Kansas ranked fifth for how often emergency room patients got those out-of-network charges. The Kansas News Service reported on that research earlier this year.

A proposal to curb surprise medical bills failed in the Kansas Legislature last spring. Other statehouses did pass such legislation this year, however, bringing to 31 the total number of states with at least some consumer protections against surprise billing.

Other ideas to require doctors and hospitals to give patients better cost estimates prior to care also failed to pass the Kansas Legislature this year.

Health care providers say calculating meaningful estimates is difficult because various billers can exist under a single roof and a patient’s care may prove more complex than originally thought. They also say patients would need to understand how the estimates fit with their own insurance plan deductibles and copays.

Hospitals are appealing a new Trump administration rule in court that could soon force them to make their prices public.

The Kansas Health Institute is a nonprofit research group that receives funding from the Kansas Health Foundation, one of the Kansas News Service’s financial supporters.

–­ The Kansas News Service, ksnewsservice.org, is a collaboration of KCUR, Kansas Public Radio, KMUW and High Plains Public Radio.