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B25.9 ICD-10-CM Code: Cytomegaloviral disease, unspecified

B25.9 maps to CMS-HCC V28 6. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · free HCC coding tools

ICD-10-CM Code View

HCC Buddy Code Card

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FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Other viral diseases (B25-B34)

B25.9

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Cytomegaloviral disease, unspecified

A viral infection caused by cytomegalovirus (CMV) where the specific affected body part or system is not documented or identified.

Buddy the Bee presenting code insight

Buddy Insight

Cytomegaloviral disease, unspecified, is used when CMV infection is documented but the specific organ system affected is not identified.

CMS-HCC V28

HCC 6

Code-level coefficient reference

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 006

Code-level coefficient reference

ESRD/PACE

HCC 6

Code-level coefficient reference

RXHCC

HCC 5

Code-level coefficient reference

Code Book Path

Official
B25Cytomegaloviral disease
B25.9Cytomegaloviral disease, unspecified

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for B25.9 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for B25.9 in this effective period.

Related Child Codes

Official
B25.0Cytomegaloviral pneumonitis
B25.1Cytomegaloviral hepatitis
B25.2Cytomegaloviral pancreatitis
B25.8Other cytomegaloviral diseases

Includes

Official

ICD-10-CM does not list Includes notes for B25.9 in this effective period.

Excludes 1

Official
  • congenital cytomegalovirus infection (P35.1)
  • cytomegaloviral mononucleosis (B27.1-)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for B25.9 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for B25.9 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for B25.9 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Confirmed CMV infection (positive CMV PCR, culture, or antigen test)
Documentation that a specific organ involvement could not be determined
Clinical context: symptoms, immunocompromised status
Plans for further diagnostic workup to identify the affected organ system

MEAT Support

HCC Buddy guidance
Confirmed CMV infection (positive CMV PCR, culture, or antigen test)
Documentation that a specific organ involvement could not be determined
Clinical context: symptoms, immunocompromised status
Plans for further diagnostic workup to identify the affected organ system

Audit Caution

HCC Buddy guidance
Using B25.9 when documentation supports a site-specific CMV code — always review the chart for organ involvement details
Not querying the provider for specificity when CMV disease is documented without organ specification
Coding CMV viremia (detectable virus in blood) as CMV disease when no organ dysfunction is present — viremia alone may not warrant a disease code
Missing CMV disease in transplant patients where prophylaxis failure or breakthrough infection occurs

Common Mistakes

HCC Buddy guidance
B25.0-B25.8 — Site-specific CMV codes; always prefer these over the unspecified code when organ involvement is documented
B27.10 (Cytomegaloviral mononucleosis without complications) — CMV mononucleosis in immunocompetent patients has a separate code
Z22.6 (Carrier of human T-lymphotropic virus type-1) — Different viral carrier state, not CMV

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is B25.9 an HCC code?

Yes. B25.9 (Cytomegaloviral disease, unspecified) maps to HCC 6, Opportunistic Infections under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.381. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: B25.9 is billable and maps to V28 HCC 6, Opportunistic Infections. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
B25.9
Description
Cytomegaloviral disease, unspecified
HCC (V28)
HCC 6 — Opportunistic Infections
RAF reference coefficient
0.381
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 6, Opportunistic Infections
0.381
ESRDHCC 6, Opportunistic Infections
Not separately weighted
RxHCCHCC 5, Opportunistic Infections
Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work B25.9 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for B25.9

For B25.9 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

  • MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
  • EEvaluate: test results, medication response, or physical findings reviewed by the provider
  • AAssess: explicit mention in the assessment or plan with acknowledgment of status
  • TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed B25.9 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

B25.9 is the ICD-10-CM diagnosis code for cytomegaloviral disease, unspecified. A viral infection caused by cytomegalovirus (CMV) where the specific affected body part or system is not documented or identified. B25.9 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering other viral diseases (b25-b34).

Under the CMS-HCC V28 risk adjustment model, B25.9 maps to Opportunistic Infections (HCC 6) with a source-labeled community, non-dual, aged reference coefficient of 0.381. No V24 mapping is shown for B25.9; use the applicable model and payment year when reviewing the V28 mapping. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Use this code only when the documentation does not specify which organ system is affected by CMV; if a specific site is documented, use a more specific B25 code. Because B25.9 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for B25.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Use this code only when the documentation does not specify which organ system is affected by CMV; if a specific site is documented, use a more specific B25 code
  • •Common in immunocompromised patients; review clinical context to determine if a more specific code applies

Clinical Significance

Cytomegaloviral disease, unspecified, is used when CMV infection is documented but the specific organ system affected is not identified. This code should prompt a query to the provider for site specification, as the clinical management and documentation quality improve with site-specific coding.

Documentation Requirements

  • ✓Confirmed CMV infection (positive CMV PCR, culture, or antigen test)
  • ✓Documentation that a specific organ involvement could not be determined
  • ✓Clinical context: symptoms, immunocompromised status
  • ✓Plans for further diagnostic workup to identify the affected organ system
  • ✓Treatment regimen documented (empiric antiviral therapy)

Commonly Confused Codes

  • •B25.0-B25.8: Site-specific CMV codes; always prefer these over the unspecified code when organ involvement is documented
  • •B27.10 (Cytomegaloviral mononucleosis without complications): CMV mononucleosis in immunocompetent patients has a separate code
  • •Z22.6 (Carrier of human T-lymphotropic virus type-1): Different viral carrier state, not CMV

Child Codes

B25.0Cytomegaloviral pneumonitis
HCC 6
B25.1Cytomegaloviral hepatitis
HCC 6
B25.2Cytomegaloviral pancreatitis
HCC 6
B25.8Other cytomegaloviral diseases
HCC 6
B25.9Cytomegaloviral disease, unspecified
HCC 6

Code Hierarchy

└B25Cytomegaloviral disease└B25.9Cytomegaloviral disease, unspecified
└B25.9Cytomegaloviral disease, unspecified

Because B25.9 maps to an HCC category, the documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment.

B25.9 maps to CMS-HCC V28 category 6, Opportunistic Infections. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for B25.9. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

Work B25.9 in HCC Buddy

Open B25.9 in the Code Book for the full Index-to-Tabular path, MEAT checklist, and V28 HCC mapping, or in the Encoder to code from a keyword search. Pro includes 7 days to try everything, no card required.

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