I think I've read that hospitals do that after a year or so; my brother-in-law had a liver transplant 20ish years ago and I know they couldn't pay (he has since died and my sister has remarried, and is fine).

http://www.creditcards.com/credit-ca...-tips-1266.php

http://www.nytimes.com/2009/03/14/health/14patient.html

http://www.cbsnews.com/stories/2006/...n1369185.shtml