A retiree's Medicare Part B coverage primarily consists of which type of healthcare services?

Medicare Part B primarily covers outpatient care, which includes a wide range of healthcare services received outside of hospitals. This coverage encompasses doctor's visits, preventive services, lab tests, and certain types of outpatient mental health services. It is designed to help beneficiaries access necessary healthcare while they are not hospitalized.

In contrast, hospital stays fall under Medicare Part A, which covers inpatient care. Ambulance services can sometimes be covered under Part B, but these are more specialized and don’t constitute the core of what Part B provides. Long-term care services are generally not covered by Medicare at all. Therefore, the focus of Medicare Part B on outpatient care highlights its essential role in providing continuity of health services for retirees who may need regular management of their conditions without requiring hospitalization.