Before paying anything
Ask billing for an itemized statement and read it. Duplicate charges and never-happened items are common enough that checking is standard practice, not paranoia.
Nonprofit hospitals must publish assistance policies (an IRS requirement); many reduce or erase bills below income multiples of the poverty line. The magic words: 'I'd like to apply for financial assistance.'
The bill must match what your insurer says you owe. Appeals exist and succeed regularly.
Self-pay discounts and lump-sum settlements are routine. Billing departments have authority scripts assume they don't.

If it's already large or in collections
Hospitals commonly offer them directly. A $4,000 bill at $120/month with no interest beats any card.
Moving hospital debt to a 22% credit card converts flexible, often-forgivable debt into the most aggressive kind.
Recent US credit-bureau policy changes removed paid medical collections and small balances from reports and delayed new ones — check current CFPB guidance for what applies now.
In many states Medicaid covers bills up to three months before application. If income qualified you at the time of care, apply anyway.
Quellen: CFPB — Medical debt · IRS — Charitable hospital financial assistance requirements