Principal Diagnosis

by  Christine Woolstenhulme, QMC QCC CMCS CPC CMRS
Mar 2nd, 2017

The official guidelines for ICD-10-CM have very specific rules in determining principal diagnosis. However, it is imperative to note that it is necessary to be aware of the coding conventions in the ICD-10-CM Tabular List and Alphabetic Index as they take precedence over the official coding guidelines. Also, consider the following:

• Review the entire record to determine the specific reason for the encounter and the conditions being treated. 

• Codes for symptoms, signs, and ill-defined conditions from Chapter 18 are not to be used as a principal diagnosis when a related definitive diagnosis has been established. 

• When there are two or more interrelated conditions (such as diseases in the same ICD-10-CM chapter or manifestations characteristically associated with a certain disease) potentially meeting the definition of principal diagnosis, either condition may be sequenced first, unless the circumstances of the admission, the therapy provided, the Tabular List, or the Alphabetic Index indicate otherwise.

• 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, the Alphabetic Index, Tabular List, or any other coding guidelines do not provide sequencing direction, any one of the diagnoses may be sequenced first.

• Sequence as a principal, diagnose the condition, which after study occasioned the admission to the hospital, even though treatment may not have been carried out due to unforeseen circumstances.

• When the admission is for treatment of a complication resulting from surgery or other medical care, the complication code is sequenced as the principal diagnosis. If the complication is classified to the T80-T88 series, and the code lacks the necessary specificity in describing the complication, an additional code for the specific complication should be assigned.

For more information see ICD-10-CM Official Guidelines for Coding and Reporting Section IV for outpatient coding and reporting.