Having unpaid medical bills can affect your credit score but you will not or cannot go to jail for not paying medical bills.
All that can happen is if you have a huge medical bill or medical bills is that they can take you to court and sue you for the unpaid medical bills.
They can then possibly seize your house through a court order to make you pay for the unpaid medical bills.
But you cannot and won't go to jail for the unpaid medical bills.
If you have unpaid medical bills you should try and work out a payment plan to pay back the medical bills so that you will not lose your possessions or home as a result.
Eventually though the medical bills will go off your credit report and you cannot be denied any medical services from a hospital should you need emergency services even when you still owe a bunch of medical bills.