Medical/Clinical Coding for Additional or Secondary Dx

Gloryanne Bryant, RHIA, CDIP, CCS, CCDS Medical Coding Leave a Comment

Medical/Clinical Coding for Additional or Secondary Dx

Throughout my career in Health Information Management, one of the particular areas of focus for both auditing and education has been the coding of an additional or secondary diagnosis. Whether inpatient (acute care) or outpatient coding, confusion and even errors occur in this area. The Official Guidelines for Coding and Reporting are at the center of understanding when, why and how to assign or select an additional/secondary diagnosis, for the inpatient (acute care) and outpatient settings alike. These “OFFICIAL” guidelines drive accuracy and compliance!

A patient’s medical record could include a long list of diagnoses, but not all of these conditions may be reportable. Coding professionals MUST determine when they can report conditions as “other” secondary diagnoses and when they must simply leave them off entirely.

There are four (4) sections to the Official Guidelines as most of you know. In “Section III” is where you find guidelines for reporting additional diagnoses in non-outpatient settings and in Section IV is for outpatient coding and reporting. Within Section III you will find guidance on the following:

  • Previous Conditions
  • Abnormal Findings
  • Uncertain Diagnosis

In Section IV (Outpatient), there are 17 different separate guidelines, but the two that we often considered for coding guidance an additional or secondary diagnosis are:

  • Chronic Diseases
  • Code All Documented Conditions That Coexist

Depending on the documentation, the secondary diagnosis needs to meet reportable criteria. Be sure to watch “clinical indicators” and possible opportunity for querying! In addition, “History of” codes (categories Z80–Z87) may be used as secondary codes if the historical condition or family history “has an impact on current care or influences treatment.” The concept of impact on current care or influence of management is the crucial point.

Clinical Documentation Integrity (CDI) specialists can help address cases in which the documentation is unclear. Unclear documentation is an unfortunate reality that many coders face when physicians suspect a condition, document it initially, rule it out mentally (but fail to provide documentation), and then simply stop documenting the condition entirely in the record.

There is an expectation that we in healthcare understand the rules, conventions, and guidelines for clinical coding. Yes, we are under scrutiny today and this is not going to let up . . . auditing is a common occurrence and to be expected. We must rely on the “Official” guidelines to achieve coding accuracy and compliance. Utilize the guidelines when auditing and conducting education.

Published through the Centers for Disease Control and Prevention (CDC), and the Center for Medicare and Medicaid Services (CMS), the “Official Guideline for Coding” or OGC as some like to call them, are available and free to the public at: 2021 ICD-10-CM Guidelines (

To summarize, the clinical coding world, “Additional or Secondary diagnosis” reporting is essential for data quality, medical necessity and to receiving the reimbursement deserved. Under reporting and this can possibly leave revenue on the table uncollected. Over reporting diagnosis (codes) can result in paying massive fines and penalties for overreporting and being noncompliant. This is true regardless of your specialty, practice size or hospital. Be sure to continue to obtain regular exterior audits to ensure accurate reimbursement. Always follow the Official Guidelines for Coding and Reporting as this is the ethical responsibility of all coding professionals.

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