Secondary Diagnosis Reporting in Inpatient Coding: Why the Details Matter

Why Accurate Secondary Diagnosis Reporting Is Critical

Understanding when a condition meets coding guidelines for reporting as a secondary diagnosis is critical to ensuring that coded data accurately represents patient care. Precise code assignment influences quality reporting, performance metrics, and reimbursement. When secondary conditions are incorrectly coded—whether through overcoding or underreporting—it can lead to significant consequences such as compliance risks, audit exposure, inaccurate quality scores, and misrepresentation of both patient acuity and organizational performance. 

Applying the Official Definition of “Other (Additional) Diagnoses”

A secondary diagnosis is reportable when it affects patient care by requiring one or more of the following: 

• Clinical evaluation: The provider assesses or monitors the condition (e.g., monitoring symptoms, evaluating serial lab tests, imaging, or specialist consultation). 
• Therapeutic treatment: The condition receives active treatment (e.g., medication management, wound care, transfusion). 
• Diagnostic procedures: Testing is performed to evaluate the condition. 
• Extended length of stay or Increased nursing care: The condition contributes to increased complexity or length of stay. 

Identifying Valid Secondary Diagnoses Through Clinical Indicators

A diagnosis listed in the past medical history or mentioned once in the record should not automatically be reported. Coders must review the chart for evidence that the condition was evaluated, treated, or influenced care.

Examples: 

• Reportable: Hypertension requiring daily medication during admission for pneumonia is reportable as a secondary diagnosis. 
• Not reportable: Glaucoma noted solely in past medical history, without current treatment or clinical impact during an admission for cholecystitis/cholecystectomy, does not meet criteria for reporting as a secondary diagnosis. 

Documentation Requirements for Secondary Diagnosis Assignment & Common Pitfalls

If documentation is unclear, inconsistent, or conflicts with clinical findings, query the provider. 

• Documentation of pancytopenia, platelets within normal range. 

Pitfalls:

• Coding incidental findings that did not impact care. 
• Assigning chronic conditions without evidence of evaluation or management. 
• Reporting resolved problems from prior admissions not addressed in current encounter. 

Annette Brehl, RHIA, CCS, CCS-P 

Senior Consultant, Quality at UASI

Annette Brehl is an Inpatient Coding Auditor and Educator at UASI, known for elevating coding quality through in-depth documentation analysis, a strong command of regulatory and coding guidelines, and targeted education. She shares coding tips informed by audit findings that helpcoders strengthen their accuracy, consistency, and confidence. 

Works Cited

Centers for Medicare & Medicaid Services. (2025). ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026.
Available at https://www.cms.gov/files/document/fy-2026-icd-10-cm-coding-guidelines.pdf