Because Allina is the dominant health system in some rural parts of Minnesota, getting kicked out can leave patients with few options.

Jennifer Blaido lives in Isanti, a small town outside Minneapolis, and Allina owns the only hospital there. Ms. Blaido, a mechanic, said she racked up nearly $200,000 in bills from a two-week stay at Allina’s Mercy Hospital in 2009 for complications from pneumonia, along with several visits to the emergency department for asthma flare-ups. Ms. Blaido, a mother of four, said that most of the hospital stay was not covered by her health insurance and that she was unable to scrounge together enough money to make a dent in the debt.

Last year, Ms. Blaido had a cancer scare, and she said she couldn’t get an appointment with a doctor at Mercy Hospital. She had to drive more than an hour to be examined at a health system unconnected to Allina.

Allina does not make this policy explicit to patients. It is not mentioned in the health system’s list of “frequently asked questions” about billing practices. In at least one case, Allina has denied that it even existed.

In a lawsuit filed last year in state court in Minnesota, Allina sued a couple, Jordan and JoLynda Anderson, for nearly $10,000 in unpaid medical bills.