Hospital based billing for offices- 72hour rule

It has been my understanding that when hospital based billing for an office visit and services (for example: EKG, ua, pulse ox, vaccines) that if the patient is then seen in the hospital within 72hours that the facility fee for the office visit (only) is written off, but not the services. Just looking for confirmation that this is correct.
Thank you.

72 hour window

Part A -Facility DRG rule - 72 hour--Medicare has a 3 Day Payment Window Rule or 72 Hour Rule – The rule states that if a patient receives diagnostic tests and hospital outpatient service within 72 hours of admission to a hospital (3-day payment window), then all such tests and services are combined with the inpatient services only if services are related to the admission.

Part B - The physician can bill any medically necessary E/M performed on day other than admit day.