Illinois residents with Obamacare plans next year won't have affordable access to some of the state's top hospitals.

Four research hospitals in Chicago will be excluded from the network of providers covered by the insurers selling on the Illinois marketplace in 2017, adding to a list of problems for Obamacare customers in the state as premiums spike and plans shrink their networks.

Patients who regularly visit the four hospitals, which include Lurie Children's Hospital, University of Chicago Medical Center, Rush University Medical Center and Northwestern Memorial Hospital, typically have serious health conditions, such as cancer, and rely on teams of specialists they can't find elsewhere.

There is a workaround for patients of Northwestern, who could get a referral from one of the hospital's primary care physicians in the western suburbs.

But other than that exception, those with marketplace plans will have to pay out of pocket or get prior authorization from their insurer if they want to keep receiving care.

Lurie Children's, a prominent pediatric specialty hospital, was the latest medical center to announce it's not included in any marketplace plan, posting a notice on its website that urged patients to get authorization from their insurer before their visit.

"Without a prior authorization, your child's care at Lurie Children's would be out-of-network," the hospital wrote this week. "This means that it is very likely you will be responsible for most or all of the costs."

The other three hospitals are linked with universities and are highly regarded. Of all the hospitals in Illinois, U.S. News and World Report has ranked Northwestern number one, Rush number two and the University of Chicago number three.