Is A81.9 a billable ICD-10-CM code?

Yes. A81.9 is a billable, specific ICD-10-CM code and is valid for submission on a claim.

Where does A81.9 sit in the tabular list?

Certain infectious and parasitic diseases (A00-B99), in the block Viral and prion infections of the central nervous system (A80-A89).

A81.9

A81.9 — Atypical virus infection of central nervous system, unspecified

Billable / specific codeICD-10-CM

A81.9 is a billable, specific ICD-10-CM code for atypical virus infection of central nervous system, unspecified. It is valid for submission on a claim.

Inclusion terms

Alternative wordings a physician may use in the chart for this same code.

Prion diseases of the central nervous system NOS

Risk adjustment

A81.9 risk-adjusts. Under the CMS-HCC V28 model it maps to this category:

HCC 127 Dementia, Mild or Unspecified0.341 RAF

Coefficient shown for the Community Non-dual Aged segment. A higher HCC in the same hierarchy will suppress this one, so capturing it does not always add score.

Medicare coverage

A81.9 is named in 2 Medicare coverage policies — 2 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

A56612Billing and Coding: CT of the Head
A57204Billing and Coding: MRI and CT Scans of the Head and Neck

How A81.9 is indexed

Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to A81.9.

Disease, diseased›prion, central nervous system
Infection, infected, infective›slow virus
Infection, infected, infective›atypical›virus
Infection, infected, infective›virus, viral NOS›slow
Infection, infected, infective›virus, viral NOS›central nervous system›atypical
Infection, infected, infective›virus, viral NOS›central nervous system›slow virus

Related codes at this level

Codes that share A81. If A81.9 is not quite right, the correct code is usually one of these.

Questions about A81.9

Is A81.9 a billable ICD-10-CM code?: Yes. A81.9 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does A81.9 sit in the tabular list?: Certain infectious and parasitic diseases (A00-B99), in the block Viral and prion infections of the central nervous system (A80-A89).