How Much Does Medicare Part B Cover? 
Medicare Part B covers services and supplies that are needed to prevent or treat diseases or health conditions . While Medicare Part A generally covers time spent in the hospital -LRB- in addition to skilled nursing facilities and some other services -RRB- , Medicare Part B generally covers medically necessary doctors ' services , hospital outpatient services , durable medical equipment , preventative care , labs and tests , ambulance , and some other services . 