The LinkedIn request was an extreme example of what happens when medical bills go unpaid. Even bills incurred in an emergency can be sent to debt collectors or sold to debt buyers, who will attempt to collect on them however they can—including, perhaps, through America’s largest professional social network. (Pollack claims the request was an error.)

To Krevat, the LinkedIn request was almost funny, in the laugh-till-you-cry sense. She remembers thinking, Is this lady stalking me or does she really think we’d be good in each others’ professional networks? “It was just more evidence that I was in this bizarro world of receiving bills I shouldn’t be responsible for,” Krevat told me.

Krevat’s bills were just a drop in the American medical-debt ocean. About 43 million Americans have unpaid medical debt dinging their credit, and half of all overdue debt on Americans’ credit reports is from medical expenses, according to a Consumer Financial Protection Bureau study from 2014. The debt typically comes from out-of-network doctors who people thought were in-network, hospital stays, or ambulance rides. About one in six Americans received a surprise out-of-network medical bill in 2017 after being treated in a hospital, even though they had insurance, according to Kaiser Health News.

In an emailed statement, the American Hospital Association told me, “Hospitals and health systems treat all patients who come through their doors, around the clock and regardless of their ability to pay. They work closely with uninsured and low-income patients on their individual bills, including discussing financial-assistance options with them.”

Krevat’s bills began to arrive while she was still being treated at Columbia University Irving Medical Center. One came from one of the hospital’s doctors, Mathew R. Williams, for $9,000. Another came from a doctor named Aziz Ghaly for $17,418. A few months later, a separate invoice from Weill Cornell Physicians said she owed $22,464.

Williams, who now works for New York University Langone Health, told me over email that decisions about billing and insurance participation were made by Columbia University Irving Medical Center, not by individual providers. In an emailed statement, a representative from Columbia said, “Unfortunately, when a patient’s insurance plan does not cover all of the costs involved in their care, the patient is responsible for the balance. We understand that unusually high health-care costs may create a financial hardship for other patients and we try to set up payment arrangements that are within their financial means.” (Ghaly told me he was a fellow at Columbia at the time. “We are on salary, and they bill for us,” he said. “I have no idea what they bill, or why it was out of network. We’re not involved in it at all. This is an unfortunate part of our health system.”)