Thanks to regular reader (and commenter) Scuzz, we learn of a horrendous example of one of our favorite memes here ("health care costs drive health insurance costs"):
"Several months after back surgery, Linda Burdick sat holding a hospital bill for almost $60,000. ... Burdick hired two billing investigators. After demanding an itemized accounting, health care navigators Lin Osborn and Beth Morgan believe Burdick was overcharged by $40,000."
That's a lot of overcharge. For example, she was charged over $1,700 (each!) for a half dozen surgical screws [ed: don't you dare - this is a family blog!]. The moral of the story is to be proactive; just because a provider says you owe additional money doesn't make it so.
And beware of balance billing: if you're in network, it's strictly forbidden. It's always a good idea to check your EOB's (Explanation of Benefits); these are the forms that your carrier will send you to let you know what charges have been paid and why.
And, of course, for more egregious cases, there are a number of claims services that can help you get to the truth. These usually involve a fee, but can literally pay for themselves with one mistaken claim.
[Hat Tip: Scuzz]