In measures that require the capture of the “Principal Diagnosis” there is the potential to have more than one principal diagnosis code. The inclusion of the provider documentation of a principal diagnosis on the problem list and the final coded diagnosis has the potential for the creation of multiple Principal Diagnoses.

Scenario:
Patient arrives to ED and provider documents Principal Diagnosis of AMI, however, the patient was also found to have Stroke. The patient was equally evaluated and treated for both diagnoses. By coding rules the patient’s Principal Diagnosis could be Stroke. This creates a situation where there would be two different Principal Diagnosis codes.

• AND: "Diagnosis, Active: (ordinality: 'Principal Diagnosis')" starts during "Occurrence A of Encounter, Performed: Encounter Inpatient"
Selection of Principal and Secondary Diagnosis(es)
Inpatient diagnoses shall be coded in accordance with Uniform Hospital Discharge Data Set (UHDDS) definitions for principal and additional diagnoses as specified in the Official Guidelines for Coding and Reporting.

a. The principal diagnosis is defined in the UHDDS as, “that condition established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care.” AHA Coding Clinic provides specific instructions for selecting the principal diagnosis for coding substance dependence, abuse and therapy. Company facilities providing these services will follow the guidelines published in the most current AHA Coding Clinic.

AHA Coding Clinic guidelines state that in the unusual instance when two or more diagnoses equally meet the criteria for principal diagnosis as determined by the circumstances of admission, diagnostic workup and/or therapy provided either may be sequenced first when neither the Alphabetic Index nor the Tabular List directs otherwise. In the case of two or more diagnoses equally meeting the criteria for principal diagnosis, in order to appropriately identify the severity of the patient, the resources used and appropriate reimbursement, the coder should sequence the principal diagnosis that results in the higher relative weighted Diagnosis Related Group (DRG) assignment. The exception to this guidance is when a procedure is performed. In this situation, the principal diagnosis most related to the principal procedure should be selected as appropriate. The facility should review any records when the extensive or non-extensive Operating Room procedure is unrelated to the principal diagnosis to determine that the principal diagnosis or surgical procedure was assigned and/or reported correctly (Source: Medicare Claims Processing Manual, Chapter 3).

b. The UHDDS defines additional diagnoses as, “all conditions that coexist at the time of admission, that develop subsequently, or that affect the treatment received and/or the length of stay.” Diagnoses that relate to an earlier episode which have no bearing on the current hospital stay are to be excluded.

1. Selection of Principal and Secondary Procedure(s)
In accordance with UHDDS definitions and the most current AHA Coding Clinic Guidelines, all significant procedures are to be reported.
a. A significant procedure is one that is: (1) surgical in nature, or (2) carries a procedural risk, or (3) carries an anesthetic risk, or (4) requires specialized training.
b. When more than one procedure is reported, the principal procedure is to be designated by following the instructions published in the most current Official Coding Guidelines for Coding and Reporting published in AHA Coding Clinic for ICD-9-CM. This designates that the principal procedure is the procedure that is most related to the principal diagnosis.

1.) If this is the case, what development guidelines should we follow?