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

Compare with another code for B25.9Check this code on a claim

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
2 Excludes1
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 6 · RxHCC V08 category 5

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too, and is marked with where it comes from.

Excludes1from B25Not reported with this code unless documented as unrelated
  • congenital cytomegalovirus infection (P35.1)
  • cytomegaloviral mononucleosis (B27.1-)

Where it sits Source: CMS/NCHS

Under:Chapter 1: Certain Infectious and Parasitic DiseasesB25-B34 Other viral diseasesB25 Cytomegaloviral disease

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 865 — VIRAL ILLNESS WITH MCC (MDC 18)
  • MS-DRG 866 — VIRAL ILLNESS WITHOUT MCC (MDC 18)
  • MS-DRG 974 — HIV WITH MAJOR RELATED CONDITION WITH MCC (MDC 25)
  • MS-DRG 975 — HIV WITH MAJOR RELATED CONDITION WITH CC (MDC 25)
  • MS-DRG 976 — HIV WITH MAJOR RELATED CONDITION WITHOUT CC/MCC (MDC 25)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 6 — Opportunistic Infections

Other models: CMS-HCC V22 HCC 6 · RxHCC V08 HCC 5

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for B25.9 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on B25.9 itself; “inherited from” names the category or block whose note applies here.

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Source: inherited from B25

Coder workflow for B25.9

MedCoder structured workflow — derived from this code’s own official record

Before you code B25.9

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, B25.9 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    ReviewB25.0, B25.1, B25.2, B25.8

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

  2. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with B25.9. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — B25.9 is appropriate when the documentation goes no further.

    ReviewB25.0, B25.1, B25.2, B25.8

  2. Does the documentation support a condition named in B25.9’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewP35.1, B27.1

Consider B25.9. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Any detail beyond this code’s title
What the record states that a more specific code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Excludes1 — check before selecting B25.9(2 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with B25.9: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareP35.1, B27.1

    See the official tabular notes · Guidelines I.A.12.a

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewB25.0, B25.1, B25.2, B25.8

Documentation: Both the condition B25.9 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewP35.1, B27.1

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse B25.9 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of B25.9 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • P35.1— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of congenital cytomegalovirus infection moves the case to P35.1; the two are not reported together unless documented as unrelated.

    Full comparison: B25.9 vs P35.1 →

  • B27.1— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of cytomegaloviral mononucleosis moves the case to B27.1; the two are not reported together unless documented as unrelated.

    Full comparison: B25.9 vs B27.1 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Cytomegaloviral disease, unspecified is a billable ICD-10-CM diagnosis code (B25.9).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • CC as a secondary diagnosis (FY2027). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name B25.9 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: B34 — Viral infection of unspecified site.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 2 Excludes2 notes: B10 — Other human herpesviruses (via B25.-), B10 — Other human herpesviruses.

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 1 Code First instruction: H67 — Otitis media in diseases classified elsewhere (via B25.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

Referenced by 1 Use Additional Code instruction: T86.43 — Liver transplant infection (via B25.-).

These codes instruct coders to additionally report this code when it applies.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 19 clinically related codes on its CMS exclusion list. Does not count toward severity when the stay groups to DRGs 974-976 (HIV with Major Related Condition).

Named in the grouper logic of 5 MS-DRGs: DRG 865 (MDC 18), DRG 866 (MDC 18), DRG 974 (MDC 25), DRG 975 (MDC 25), DRG 976 (MDC 25).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):INF008 — Viral infection (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

A96.0 — Junin hemorrhagic fever, A96.1 — Machupo hemorrhagic fever, A96.2 — Lassa fever, A96.8 — Other arenaviral hemorrhagic fevers, A96.9 — Arenaviral hemorrhagic fever, unspecified, A98.3 — Marburg virus disease, A98.4 — Ebola virus disease, A98.5 — Hemorrhagic fever with renal syndrome, B25.8 — Other cytomegaloviral diseases, B33.24 — Viral cardiomyopathy, B33.3 — Retrovirus infections, not elsewhere classified, B33.4 — Hantavirus (cardio)-pulmonary syndrome [HPS] [HCPS], B33.8 — Other specified viral diseases, B34.0 — Adenovirus infection, unspecified, B34.1 — Enterovirus infection, unspecified, B34.2 — Coronavirus infection, unspecified, B34.4 — Papovavirus infection, unspecified, B34.8 — Other viral infections of unspecified site

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Opportunistic Infections) for risk-adjusted payment.

A07.2 — Cryptosporidiosis, A31.0 — Pulmonary mycobacterial infection, A31.2 — Disseminated mycobacterium avium-intracellulare complex (DMAC), B25.0 — Cytomegaloviral pneumonitis, B25.1 — Cytomegaloviral hepatitis, B25.2 — Cytomegaloviral pancreatitis, B25.8 — Other cytomegaloviral diseases, B37.1 — Pulmonary candidiasis, B37.7 — Candidal sepsis, B37.81 — Candidal esophagitis, B44.0 — Invasive pulmonary aspergillosis, B44.1 — Other pulmonary aspergillosis, B44.2 — Tonsillar aspergillosis, B44.7 — Disseminated aspergillosis, B44.89 — Other forms of aspergillosis, B44.9 — Aspergillosis, unspecified, B45.0 — Pulmonary cryptococcosis, B45.1 — Cerebral cryptococcosis, B45.2 — Cutaneous cryptococcosis, B45.3 — Osseous cryptococcosis, +16 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Viral infection).

+309 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Virus, viral”; these codes share that main term but sit in a different category of the Tabular List.

A92.30 — West Nile virus infection, unspecified (West Nile), A92.31 — West Nile virus infection with encephalitis (West Nile, with, encephalitis), A92.32 — West Nile virus infection with other neurologic manifestation (West Nile, with, optic neuritis), A92.39 — West Nile virus infection with other complications (West Nile, with, complications NEC), B34.8 — Other viral infections of unspecified site (specified NEC), B97.4 — Respiratory syncytial virus as the cause of diseases classified elsewhere (respiratory syncytial, as cause of disease classified elsewhere), B97.89 — Other viral agents as the cause of diseases classified elsewhere (as cause of disease classified elsewhere), J06.9 — Acute upper respiratory infection, unspecified (respiratory syncytial, upper respiratory infection), J09.X2 — Influenza due to identified novel influenza A virus with other respiratory manifestations (swine influenza), J12.1 — Respiratory syncytial virus pneumonia (respiratory syncytial, pneumonia), J20.5 — Acute bronchitis due to respiratory syncytial virus (respiratory syncytial, bronchitis), J21.0 — Acute bronchiolitis due to respiratory syncytial virus (respiratory syncytial, bronchiolitis)

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Gamma-glutamyl Transferase (GGT) Test, HIV Screening Test

Contextual Map

Every relationship of B25.9 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run B25.9 with these 4 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes

Referenced by Code First instructions

Referenced by Use Additional Code instructions

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 6 — Opportunistic Infections [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

MDC crossing

  • MDC 18 — Infectious and Parasitic Diseases, Systemic or Unspecified Sites[MDC crossing]: “Infectious and Parasitic Diseases, Systemic or Unspecified Sites — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 1 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027
  • MDC 25 — Human Immunodeficiency Virus Infections[MDC crossing]: “Human Immunodeficiency Virus Infections — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”— CMS MS-DRG Definitions Manual · FY2027

Index entries (9)

  • Cytomegalovirus infection[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disease, diseased, cytomegalic inclusion (generalized)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disease, diseased, cytomegaloviral[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disease, diseased, inclusion[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disease, diseased, inclusion, salivary gland[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disease, diseased, salivary gland or duct, inclusion[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disease, diseased, salivary gland or duct, virus[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Infection, infected, infective (opportunistic), cytomegalovirus, cytomegaloviral[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • and 1 more

Nearest codes

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Indexed Clinical Terms (9)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "B25.9 — Cytomegaloviral disease, unspecified." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/b25.9-cytomegaloviral-disease-unspecified

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Cytomegaloviral disease, unspecified

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to B25.9 in its code family, with their registry titles.

View all codes in the B25 family