Medical bills can be wiped out with filing bankruptcy however you usually have to file bankruptcy against other debts as well if you file bankruptcy on the medical bills.
Secured debt though is not covered under bankruptcy so if you have any secured debt then you'll still owe for those debts but credit cards and medical bills can be eliminated by filing for bankruptcy.
Keep in mind though that filing bankruptcy costs a fee and it will ruin your credit at least for awhile so only file bankruptcy as the last resort.