A81.9 ICD-10-CM Code: Atypical virus infection of central nervous system, unspecified
A clear reference for the official code description, hierarchy, and related coding information from the FY 2027 U.S. release.
Code definition
Official description
A81.9Atypical virus infection of central nervous system, unspecified
ICD-10-CM diagnosis code · United States clinical modification
Classification
Where A81.9 sits
- 1
Chapter 1
Certain infectious and parasitic diseases (A00-B99)
- 2
Section
Viral and prion infections of the central nervous system (A80-A89)
- 3
Category A81
Atypical virus infections of central nervous system
- 4
Code A81.9
Atypical virus infection of central nervous system, unspecified
Documentation details
Notes for this code
Inclusion terms
- Prion diseases of the central nervous system NOS
Code first
No “code first” instruction is listed for A81.9.
Use additional code
No “use additional code” instruction is listed for A81.9.
Excludes1
Conditions that should not be reported together with this code.
No Excludes1 note is listed for A81.9.
Excludes2
Conditions not included here that may be reported separately when present.
No Excludes2 note is listed for A81.9.
Transparency
Source and release
This reference is generated from Vero’s ICD-10-CM description, hierarchy, and code-note dataset. The visible content and structured data share that source.
Review the CDC/NCHS ICD-10-CM sourceCode-specific guidance
Frequently asked questions
What does ICD-10-CM code A81.9 mean?
A81.9 is the FY 2027 U.S. ICD-10-CM code for “Atypical virus infection of central nervous system, unspecified.”
Is A81.9 a billable or specific ICD-10-CM code?
Yes. In the FY 2027 reference data used on this page, A81.9 has no child codes and is presented as a billable/specific code. Always confirm the active code set and payer requirements before use.
Where is A81.9 located in ICD-10-CM?
A81.9 is listed in Chapter 1, Certain infectious and parasitic diseases (A00-B99), within Viral and prion infections of the central nervous system (A80-A89) (A80–A89), under category A81, Atypical virus infections of central nervous system.
What coding notes are listed for A81.9?
Its listed inclusion terms are Prion diseases of the central nervous system NOS. No code-first instruction is listed. No Excludes1 note is listed. No Excludes2 note is listed.
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