If you've recently learned that you need to enter a hospital for surgery or another reason, your main focus should be to get the best care possible. But understanding what your medical insurance covers and what it doesn't is also essential. And it might help you avoid some unwelcome surprises when the hospital bills arrive.

While some out-of-pocket expenses are inevitable, there's a lot you can do to prevent unnecessary hospital costs and identify billing errors. Call your insurance carrier to verify critical features of your plan, including:

If possible, ask for all this information in writing from your insurer. At a minimum, take notes on all conversations yourself, including date and the name and contact number of the person with whom you spoke. And save all communications you get from your insurer in case you run into a payment dispute later.