Elizabeth Woodruff drained her retirement account and took on three jobs after she and her husband were sued for nearly $10,000 by the New York hospital where his infected leg was amputated.

Ariane Buck, a young father in Arizona who sells health insurance, couldn’t make an appointment with his doctor for a dangerous intestinal infection because the office said he had outstanding bills.

Allyson Ward and her husband loaded up credit cards, borrowed from relatives, and delayed repaying student loans after the premature birth of their twins left them with $80,000 in debt. Ward, a nurse practitioner, took on extra nursing shifts, working days and nights.

“I wanted to be a mom,” she said. “But we had to have the money.”

The three are among more than 100 million people in America ― including 41% of adults ― beset by a health care system that is systematically pushing patients into debt on a mass scale, an investigation by KHN and NPR shows.

The investigation reveals a problem that, despite new attention from the White House and Congress, is far more pervasive than previously reported. That is because much of the debt that patients accrue is hidden as credit card balances, loans from family, or payment plans to hospitals and other medical providers.