Under the inpatient prospective payment system (IPPS), there is a three-day payment window (formerly referred to as the 72-hour rule). This rule requires that outpatient preadmission services that are provided by a hospital up to three calendar days prior to a patient's inpatient admission be covered by the IPPS MS-DRG payment for
- diagnostic services.
- therapeutic (or non-diagnostic) services whereby the inpatient principal diagnosis code (ICD-9-CM) exactly matches the code used for pre-admission services.
- therapeutic (or non-diagnostic) services whereby the inpatient principal diagnosis code (ICD-9-CM) does not match the code used for pre-admission services.
- both A and B.