CMS Three Day Rule

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The Centers for Medicare/Medicaid Services (CMS) 3 day rule necessitates that all outpatient diagnoses and treatments are pertinent to the inpatient admission for 72 hours prior to admission.

  • The three-day rule allows inpatient diagnoses to be made using clinical data (vital signs, labs, imaging, provider documentation, etc.) gathered from EMS services as well as the initial ER evaluation.

Case Example: Patient has documentation to support worsening shortness of breath with respiratory distress and hypoxia (81% on room air) documented in the ambulance and ER records. This data supports the pulmonologist’s diagnosis of acute respiratory failure that was documented on the pulmonary consultation and was treated with nebs, steroids and oxygen.

  • The diagnosis of acute respiratory failure can be made at the time of the admission using the information obtained up to 3 days prior to admission.
  • This is a valid diagnosis which should be documented, coded and included in the inpatient DRG assignment.

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