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Data Element Name:  Principal/Primary Diagnosis Code
SPARCS Data Element Number:  49
Record Positions:  1327 - 1332 Format-Length:  A/N - 6
Effective Date:  1/1/1994 Revision Date:  December 1996


The Principal Diagnosis is the condition established after study to have been chiefly responsible for the provision of an outpatient ambulatory surgery service to a patient at the hospital or free-standing center. Since the principal diagnosis reflects clinical findings, it may differ from Admitting / Patient's Reason for Visit diagnosis.

Codes and Values:
  1. Must have been a valid ICD-9-CM code excluding decimal points. To have been valid, ICD-9-CM codes must have been entered at the most specific level to which they are classified in the ICD 9 CM Tabular List. Three digit codes further divided at the four digit level must have been entered using all four digits. Four digit codes further sub-classified at the five digit level must have been entered using all five digits. Failure to enter all required digits in the diagnosis codes would have caused the record to be rejected.

  2. Must have been left justified and entered exactly as shown in the ICD-9-CM coding reference, excluding the decimal point, and space filled.

  3. Manifestation and Unacceptable Principal Diagnosis conditions as indicated by the edit flag on the ICD-9-CM reference file were invalid.

  4. E-codes were not valid as Principal Diagnosis Codes.
Edit Applications:
  1. Edits pertaining to ICD-9-CM codes are validated on the basis of the Discharge Date (Data Element 6) and Expected Principal Reimbursement (Data Element 21) depending on conditions described in Appendix N, which includes age-specific and sex-specific diagnosis code conditions.

  2. When the edit flag on the ICD-9-CM reference file indicates an "unacceptable principal diagnosis without a secondary diagnosis" an Other Diagnosis Code 1-14 (Data Element 50) must have been reported.

  3. Diagnosis codes reported in the range of 800.00-999.99 required the reporting of a valid External Cause-of-Injury Code (Data Element 57) unless as an exception in Appendix N.