What’s the difference between preventive services and diagnostic services?

Preventive services are services you get when you are symptom-free and have no reason to think you are sick. These services may include immunizations, routine cholesterol checks, pap tests, and blood pressure screenings. They're covered at no extra cost.

Diagnostic services, on the other hand, are services you get when you have symptoms of an illness or risk factors that might indicate a health problem. These services may include chest X-rays, thyroid tests, EKGs, urine tests, and iron level testing. You may be responsible for some out-of-pocket costs for these.