It probably comes as no surprise that a hospital stay can be outrageously expensive. But did you ever actually stop and read your hospital bill? That extra pillow you asked for -- $45 please; and the test you had yesterday -- it's on your bill twice; and what about those three lines at the bottom of your bill that look like Greek?

Don't let them overcharge you one penny! Here are the most common ways hospitals take advantage of patients and how you can make sure it doesn't happen to you.

Charging You for Services You Never Received

Hospitals are notorious for charging patients for services, tests and medications which the patients never received. One study looked at 40,000 hospital bills and found 97% had errors! (Most in favor of the hospital, of course.) And since hospital bills can be written in what seems like a foreign language, it can be hard to tell if you're being overcharged or not.

To make sure you're only paying for care you actually received, keep track of the tests you're given and the medicine you take. Take a pocket notebook with you to the hospital.

During your stay, jot down who came to talk to you, what you talked about, and how long they stayed. If you're not able to do this yourself (if you're sedated, for example), then ask a friend or relative to keep a record for you.

You probably won't be able to keep track of everything, but this will give you a good start when you size up your bill. When you get your bill, question every charge you don't recognize. It's your pocket the money's coming out of, so don't be shy!

Common ways hospitals run up your bill include charging you for:

• lab tests or X-rays that were scheduled, but never performed;
• oxygen tanks and breathing masks you're no longer using;
• drugs which were prescribed for you but were returned or never taken;
• supplies the doctor ordered for you in advance but didn't use.

Making Clerical Errors

There's nothing suspicious here, people just make mistakes. You may be charged twice for the same test, or charged for a service your roommate received. By keeping a record of services, tests and medications you receive, you can catch these errors and have them removed from your bill right away. Some of the most common clerical errors include being charged for the wrong type of room (private instead of semiprivate) and being charged $500 for a $50 X-ray.

Straight Talk Tip: Always ask for an itemized bill, not a summary, so you can see every charge in detail.

For help deciphering and managing medical expenses, we recommend a great software program - INTUIT's "Medical Expense Manager 2.0," available for $49.99.

Learn more about correcting mistakes on your hospital bill by clicking here to read our special article.