Even with health insurance, being hospitalized can cost hundreds, if not thousands, of dollars. You may not be able to avoid a hospital stay, but you may be able to trim costs.

If you are in a consumer-directed health plan, like a medical savings account, knowing how to cut your costs is even more important. These plans place more responsibility for health care decisions on your shoulders.

• Be sure you understand your health insurance policy. Read your manual and updates as they arrive. Ask your supervisor or employee-benefits staff to explain any rule you find unclear. For instance, you could have to pay 50% of the costs if your plan requires pre-approval and a second opinion for surgery and you don't comply.
• Find out if you have to send the bills to the insurance company yourself. Or if your doctor's office and hospital will send them.
• Ask your doctor if routine tests can be done before you're hospitalized. For instance, it may be less costly to have blood tests and chest X-rays as an outpatient.
• Pay attention to check-in and checkout times. Save the cost of an extra night's stay and ask to check in the day of your procedure, rather than the night before.
• Find out if the hospital has progressive care, or step-down units. This is where healthier patients can get a reduced level of care at a cost savings.
• Get as much of your treatment pre-approved by your health plan as possible. You won't have to fight for coverage later.
• Ask your doctor to tell you of all visits by other doctors. Ask if the visits are required for your recovery, because you'll be billed for them. Many hospitals use hospitalists now. These are doctors who only see hospital patients. Your own doctor may never see you in the hospital. Make sure the hospital doctor knows who you are.
• Avoid weekend and holiday admissions. Unless your surgery is an emergency, you may get less medical care but will still be billed for your room.

Check your bill as soon as you can after you are discharged. To keep from being overcharged, ask for a detailed, itemized invoice. You don't necessarily need to review your bill before you leave the hospital. You may not feel well when leaving, and you shouldn't be making financial decisions then. You will have time to dispute any questionable charges.

Be on the lookout for:

• Medicines or supplies not provided. For instance, make sure you're not billed for medicines to take at home that you did not accept.
• Services not provided. For instance, your doctor may have ordered a test, then canceled it. Or you may have been scheduled for 10 treatments from physical, speech, or other therapists but received only 8.
• Phantom charges. Hospitals often bundle common procedures into packages that include a standard set of services, all of which are billed to patients. For instance, even if you didn't use the delivery room or anesthesia when delivering a baby, the hospital may bill you for them.
• Duplicate billings. Be sure you are not billed more than once for the same test or procedure.
• Inconsistencies. A test that cost $50 on Monday shouldn't cost $100 on Friday.

Call the hospital billing office and ask for an adjustment for any errors. If you have trouble resolving your complaint, talk with your insurance company, employee-benefits department, or your state's Department of Consumer Affairs.