Can one negotiate payment on medical bills after the fact?

After someone has a medical procedure completed they receive a bunch of bills from the hospital and doctors. Prior to a procedure they don’t tell you the costs, and if they say anything it is more like a range not a set price.

After the procedure when one receives the bills can they negotiate and haggle to pay less than billed for or is that stealing?

I do know that if I agreed to a price for something and then try to haggle after the fact it is stealing. Are these medical bills the same?

Since you never agreed to a set price before the procedure and only after the fact they are sending you bills you may now negotiate on the price.

If a price was discussed beforehand and now after the fact you want to negotiate to pay less, that is not permitted. You agreed to the price and they did the work so now you owe them the full agreed upon amount.