The next time you receive a medical bill, take a close look at it line by line.

A certain type of fee is popping up on more and more bills, and experts say it can range anywhere from a couple bucks to $1,000.

"That’s the facility fee. They bill the insurance company $212, but they knock it down to $60.21," said Paul Paoli, who said he was surprised to see an unexpected $60.21 charge for his last doctor's appointment.

It wasn't for his cancer treatment, but rather for a "facility fee" for his hospital visit. The explanation of benefits does not detail what the facility fee covers.  

"It's not transparent, you know, because most of us are used to a copay and you pay it and you're down the road, and then now this has come up," said Paoli.

Facility fees are becoming more common across the country.

Abe Scarr with the Public Interest Research Group of Illinois explained why.

"More and more we're seeing these mega health systems, hospital systems, and as they grow and have more market power, that's when we start to see things like this, these arbitrary fees that they're only able to get away with because consumers don't really have much choice," said Scarr.

Scarr said knowing how much the fees may cost can be hard to predict.

"They don't work in any predictable way. So we've seen them as small as $4 and up to $1,000. And they're often not disclosed until after the fact. So it's not necessarily a percentage of your bill, or anything tied to any other part of your bill. It's a tacked-on fee," said Scarr.

As Paoli learned, asking for the cost of the facility fee at the time you schedule your appointment may not lead to a clear answer.

"I said, 'What's the facility fee?' And he goes, 'Well, there's going to be a fee, but I can't tell you what it is.' I go, 'What do you mean?' 'Well it depends on how long or this or that,'" said Paoli.

According to a new report from PIRG, 15 states across the country passed laws about facility fees. Illinois and Wisconsin are not included in the list, but last year, Indiana passed a law requiring more transparency about facility fees.

Connecticut, Colorado, Maryland, New York, Ohio, Texas and Washington state all passed laws either restricting or banning facility fees on patient’s medical bills.

Scarr said if you're billed this fee, you can try disputing it.

"Bring it up with your insurer, contest it with the hospital or provider, and file a complaint with the Consumer Financial Protection Bureau or here in Illinois with the Attorney General's Office. I can't say that that's going to be successful, any of those disputes, but it's always worth trying," said Scarr.

After he spoke up, Paoli got his insurance company to cover the entire cost of his facility fee.

"I can afford it, but not everybody can afford it," said Paoli.