What Is The Difference Between Medicare A And Medicare B? 
Medicare Part A covers most hospital INPATIENT charges . The operative word here is inpatient . The hospital ER -LRB- emergency room -RRB- is considered outpatient , even though it is physically attached to the hospital . If you are `` admitted '' for observation this is also an outpatient procedure , even if you are in observation for more than 24 hours . Outpatient expenses are covered under Medicare Part B. 