Even after you're admitted, you might get a CT or MRI scan, so here's what you need to know. A CT (computed tomography) scanner takes multiple X-rays of your body and assembles the "slices," as thin as 1/50th of an inch, into a 3-D image. You will get an IV injection of a contrast dye first, to highlight the tissue of interest. Then you'll lie flat on a table and positioned inside a ring like a large doughnut.
Ninety percent of hospital bills have errors of some kind, estimates Mary Jane Stull, president of the Patient's Advocate, a South Bend, Ind., firm paid by befuddled patients to intercede on their behalf. "But it's not always intentional," she says. "You find just as many mistakes for things they've forgotten to charge you for as you find overcharges."