What is the difference between a Principal and an Other Diagnosis in UB-04?

• A. Principal diagnosis is the main reason for admission.
• B. Other diagnoses are the same as the principal diagnosis.
• C. Other diagnoses are additional conditions that affect the encounter.
• D. Principal diagnosis is optional.

Answer: (C)

On UB-04, the main reason the patient is admitted is captured as the principal diagnosis. Other diagnoses are the additional conditions that exist at admission or develop during the stay and affect how the patient is treated. They’re coded separately to reflect the full clinical picture and can include comorbidities or complications that influence care, resources, and outcomes. For example, a patient admitted for pneumonia might also have diabetes noted as another diagnosis because it affects treatment decisions and monitoring. So the difference is that the principal diagnosis is the primary reason for admission, while other diagnoses are secondary conditions that impact care.