Tatyana Schum was at home with her dogs when a burning sensation ripped through her body."Unbelievable pain like I've never felt before," said Schum.The pain was from an inflamed gallbladder that had to be removed in emergency surgery.And that 90-minute procedure produced about $18,000 in bills."$18,000 seems a little bit crazy," said Schum. "But then how do you know?You don't, according to Dr. Gerard Anderson, the Director of the Johns Hopkins Center for Hospital Finance and Management."If you go to a hospital in the United States and you want to know what you're going to get charged for an MRI or a day in the hospital or anything,they're not going to tell you. And they're not required to tell you by law," said Anderson."That's hard for me to swallow and I'll tell you why - it's because everybody's going to need a hospital at some point," said Schum.We took Schum's bill to Michelle Katz, a nurse and health care consultant. She's written two books on how to bring down hospital costs.Katz says patients can look out for additional charges or errors in bill coding."You know when you're typing on your iPhone and you accidentally push "P" instead of "O"?That happens to people, and unfortunately it may be a code that's $50 compared to a code that's $1,000," said Katz.Take a look at Schum's charges. Gallbladder surgery is seen as a moderate problem, or Level 3 in "hospital speak."But here you see she was charged for a hospital stay with a Level 4 - or high severity - problem.