Using Radiology to Improve Ischemic Stroke (CVA) Coding Specificity

Why Radiology Matters in Ischemic Stroke Coding

Once a provider has diagnosed an acute ischemic stroke or cerebral infarction, coders may use radiology reports interpreted by a physician to support:

• Location of artery involved
• Laterality
• Confirmation of infarction

This approach is supported by long-standing AHA Coding Clinic guidance, which allows use of diagnostic studies to provide specificity after the diagnosis itself has been established.

However, radiology has limits.

Important Clarification: What Radiology Can and Cannot Support

Radiology may support where the infarction occurred, but it cannot be used to infer mechanism unless the provider documents it.

AHA Coding Clinic, First Quarter 2024 reinforced this principle by clarifying that:

• Identifying an artery alone (e.g., posterior cerebral artery territory) does not justify assigning a mechanism-specific code
• When occlusion, stenosis, embolism, or thrombosis is not documented, coders must not assume the cause

In these cases, the infarction may still be coded with location specificity when supported — but mechanism-based I63 subcategories require explicit documentation.

Practical Coding Guidance for CVA Documentation

• Use radiology to support location and laterality
• Assign mechanism-specific I63 codes only when documented
• Do not infer occlusion, embolism, stenosis, or thrombosis from imaging alone
• Do not default to I63.9 if location is clearly supported but mechanism is not required for the selected code

CVA Coding Example Using Radiology Findings

• Discharge Summary: “Acute ischemic stroke.”
• MRI Brain: “Acute infarct involving the left middle cerebral artery territory.”
• No documentation of occlusion, stenosis, embolism, or thrombosis.
• Correct Coding: I63.89 — Other cerebral infarction
• Radiology supports location, but without documented mechanism, a mechanism-specific MCA code is not appropriate.

Why Accurate Use of Radiology Matters for CVA Coding

• Encourages appropriate specificity without overcoding
• Reduces unnecessary use of I63.9 when location is documented
• Prevents audit risk from inferred mechanisms
• Aligns coding with both historic and current Coding Clinic guidance

When to Query the Provider for Stroke Documentation

A query should be considered when:

• CVA is referenced during the stay but not addressed at discharge
• Imaging identifies a specific artery, but the diagnosis is unclear
• Conflicting documentation exists regarding stroke type or etiology

Documentation Accuracy and Audit Risk Considerations

Correct application of this guidance:

• Prevents inappropriate use of I63.9 when specificity is supported
• Maintains compliance with uncertain diagnosis rules
• Improves data accuracy, SOI/ROM capture, and audit defensibility

The key distinction is diagnosis vs. specificity — imaging can support the latter, but never establish the former.

Bonus Coding Tip: NIH Stroke Scale (NIHSS)

When an acute CVA is documented, review the record for an NIH Stroke Scale (NIHSS) score. NIHSS may be reported as a secondary code when documented by a provider during the inpatient stay.

• Code category: R29.7
• Assign the code based on the final NIHSS score documented
• NIHSS does not need to appear in the discharge summary if clearly documented elsewhere in the record
• If multiple scores are documented, report the initial score (facilities may choose to capture multiple scores)
• NIHSS can be captured from documentation by clinicians other than the patient’s provider

Example: NIHSS score of 8 → R29.708

Capturing NIHSS improves stroke severity reporting and supports a more complete clinical picture.



Jessica Lutz, MBA, RHIA, CCS 
AHIMA Microcredential: Auditing: Inpatient Coding   

Senior Consultant, Audit at UASI

Jessica Lutz serves as a Senior Consultant in Auditing at UASI and is recognized for her ICD-10-CM/PCS expertise and inpatient coding background. She shares coding tips from an auditor’s perspective, highlighting common pitfalls and practical ways coders and CDI teams can improve accuracy and documentation quality. 

Works Cited:

Centers for Disease Control and Prevention. (2024). ICD-10-CM Official Guidelines for Coding and Reporting, FY 2025: Section II.H. Available at: https://www.cdc.gov/nchs/data/icd/10cmguidelines-FY2025.pdf

American Hospital Association. (2014). Cerebral infarction coding guidance. AHA Coding Clinic for ICD-10-CM, Third Quarter 2014.

American Hospital Association. (2024). Radiology documentation and cerebral infarction specificity. AHA Coding Clinic for ICD-10-CM, First Quarter 2024.

The Haugen Group. (n.d.). ICD-10-CM stroke coding: The why behind the codes (Webinar Q&A). Available at: https://www.thehaugengroup.com/cm-stroke-coding-q-a/

Arizona Health Information Management Association (AzHIMA). (2025). Unlocking the full potential of stroke coding and documentation. Available at: https://www.azhima.org/annualmeeting/wp-content/uploads/2025/06/Unlocking-the-Full-Potential-of-Stroke-Coding-and-Documentation.pdf