B17.9 ICD-10-CM Code: Acute viral hepatitis, unspecified

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for B17.9 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on B17.9 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for B17.9

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

Before you code B17.9

1. Unspecified does not mean incorrect. When the record gives no greater specificity, B17.9 may be the appropriate code. Check the record for detail that supports a more specific sibling — in this subcategory the siblings differ by acute versus chronic. 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).

   ReviewB17.0, B17.1, B17.2, B17.8

   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 B17.9. 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 — B17.9 is appropriate when the documentation goes no further.

   ReviewB17.0, B17.1, B17.2, B17.8

2. Does the documentation support a condition named in B17.9’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.

   ReviewB94.2

Consider B17.9. 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).

Acuity

Acute or chronic as documented; when both are documented and separate codes exist, both are reported with the acute code first (Guidelines I.B.8).

Any detail beyond this code’s title

What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

• Excludes1 — check before selecting B17.9(1 note)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with B17.9: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareB94.2

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

• Excludes2 — not part of B17.9(2 notes)

  Coding workflow: The conditions named in this note are not included in B17.9. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  CompareB25.1, B00.81

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

Coding decision scenarios

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

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.

Indexed Clinical Terms (5)

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.

• Hepatitis, acute
• Hepatitis, acute, infectious
• Hepatitis, acute, viral (see also, Hepatitis, viral)
• Hepatitis, infectious, infective, acute (subacute)
• Hepatitis, viral, virus, acute

Don’t confuse B17.9 with…

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

The codes most likely to be picked instead of B17.9 — 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.

• B94.2— 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 sequelae of viral hepatitis moves the case to B94.2; the two are not reported together unless documented as unrelated.

  Full comparison: B17.9 vs B94.2 →

• B25.1— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of cytomegaloviral hepatitis adds B25.1; it is not part of this code and both may be reported when both are documented.

  Full comparison: B17.9 vs B25.1 →

• B00.81— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of herpesviral [herpes simplex] hepatitis adds B00.81; it is not part of this code and both may be reported when both are documented.

  Full comparison: B17.9 vs B00.81 →

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.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). 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 structured relationships — computed from published CMS and AHRQ datasets

Other codes that name B17.9 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 4 Excludes1 notes: K73 — Chronic hepatitis, not elsewhere classified (via B17.-), K75.2 — Nonspecific reactive hepatitis (via B17.-), K75.3 — Granulomatous hepatitis, not elsewhere classified (via B17.-), K75.9 — Inflammatory liver disease, unspecified (via B17.-).

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

Referenced by 11 Excludes2 notes across 2 chapters: K70 — Alcoholic liver disease (via B17.-), K70-K77 — Diseases of liver (K70-K77) (via B17.-), K71 — Toxic liver disease (via B17.-), K72 — Hepatic failure, not elsewhere classified (via B17.-), K73 — Chronic hepatitis, not elsewhere classified (via B17.-), K74 — Fibrosis and cirrhosis of liver (via B17.-), K75 — Other inflammatory liver diseases (via B17.-), K75.0 — Abscess of liver, K76 — Other diseases of liver (via B17.-), K77 — Liver disorders in diseases classified elsewhere (via B17.-), T80.6 — Other serum reactions (via B17.-).

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

Referenced by 2 Code First instructions across 2 chapters: H67 — Otitis media in diseases classified elsewhere (via B17.-), M02 — Postinfective and reactive arthropathies (via B17.-).

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 Code Also instruction: K74 — Fibrosis and cirrhosis of liver (via B17.-).

These codes suggest coding this condition alongside when both are present.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 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 40 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 5 MS-DRGs: DRG 441 (MDC 07), DRG 442 (MDC 07), DRG 443 (MDC 07), DRG 791 (MDC 15), DRG 793 (MDC 15).

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

Clinical classification (AHRQ CCSR):INF007 — Hepatitis (default); INF008 — Viral infection.

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.

B15.9 — Hepatitis A without hepatic coma, B16.0 — Acute hepatitis B with delta-agent with hepatic coma, B16.1 — Acute hepatitis B with delta-agent without hepatic coma, B16.2 — Acute hepatitis B without delta-agent with hepatic coma, B16.9 — Acute hepatitis B without delta-agent and without hepatic coma, B17.0 — Acute delta-(super) infection of hepatitis B carrier, B17.10 — Acute hepatitis C without hepatic coma, B17.11 — Acute hepatitis C with hepatic coma, B17.2 — Acute hepatitis E, B17.8 — Other specified acute viral hepatitis, B18.0 — Chronic viral hepatitis B with delta-agent, B18.1 — Chronic viral hepatitis B without delta-agent, B18.2 — Chronic viral hepatitis C, B18.8 — Other chronic viral hepatitis, B18.9 — Chronic viral hepatitis, unspecified, B19.0 — Unspecified viral hepatitis with hepatic coma, B19.10 — Unspecified viral hepatitis B without hepatic coma, B19.11 — Unspecified viral hepatitis B with hepatic coma, B19.20 — Unspecified viral hepatitis C without hepatic coma, B19.21 — Unspecified viral hepatitis C with hepatic coma, +19 more

Same clinical category (CCSR)

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

B15.9 — Hepatitis A without hepatic coma, B16.0 — Acute hepatitis B with delta-agent with hepatic coma, B16.1 — Acute hepatitis B with delta-agent without hepatic coma, B16.2 — Acute hepatitis B without delta-agent with hepatic coma, B16.9 — Acute hepatitis B without delta-agent and without hepatic coma, B17.0 — Acute delta-(super) infection of hepatitis B carrier, B17.10 — Acute hepatitis C without hepatic coma, B17.11 — Acute hepatitis C with hepatic coma, B17.2 — Acute hepatitis E, B17.8 — Other specified acute viral hepatitis, B18.0 — Chronic viral hepatitis B with delta-agent, B18.1 — Chronic viral hepatitis B without delta-agent, B18.2 — Chronic viral hepatitis C, B18.8 — Other chronic viral hepatitis, B18.9 — Chronic viral hepatitis, unspecified, B19.0 — Unspecified viral hepatitis with hepatic coma, B19.10 — Unspecified viral hepatitis B without hepatic coma, B19.11 — Unspecified viral hepatitis B with hepatic coma, B19.20 — Unspecified viral hepatitis C without hepatic coma, B19.21 — Unspecified viral hepatitis C with hepatic coma, +300 more

Same Index main term, other category

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

A50.59 — Other late congenital syphilis, symptomatic (syphilitic, congenital, late), A51.45 — Secondary syphilitic hepatitis (syphilitic, secondary), A52.74 — Syphilis of liver and other viscera (syphilitic), B00.81 — Herpesviral hepatitis (herpesviral), B15.0 — Hepatitis A with hepatic coma (epidemic, with hepatic coma), B15.9 — Hepatitis A without hepatic coma (epidemic), B16.0 — Acute hepatitis B with delta-agent with hepatic coma (D, acute, with hepatic coma), B16.1 — Acute hepatitis B with delta-agent without hepatic coma (D), B16.2 — Acute hepatitis B without delta-agent with hepatic coma (B, acute, with, hepatic coma), B16.9 — Acute hepatitis B without delta-agent and without hepatic coma (B, acute), B18.0 — Chronic viral hepatitis B with delta-agent (D, chronic), B18.1 — Chronic viral hepatitis B without delta-agent (B, chronic), B18.2 — Chronic viral hepatitis C (C, chronic), B18.8 — Other chronic viral hepatitis (viral, virus, chronic, specified NEC), B18.9 — Chronic viral hepatitis, unspecified (viral, virus, chronic), B19.0 — Unspecified viral hepatitis with hepatic coma (viral, virus, with hepatic coma), B19.10 — Unspecified viral hepatitis B without hepatic coma (B), B19.11 — Unspecified viral hepatitis B with hepatic coma (B, with), B19.20 — Unspecified viral hepatitis C without hepatic coma (C), B19.21 — Unspecified viral hepatitis C with hepatic coma (C, with hepatic coma), +30 more

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, Hepatitis Testing, HIV Screening Test, Iron Panel, Partial Thromboplastin Time (PTT) Test, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of B17.9 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 B17.9 with these 13 related codes in Claim Check

Hierarchy

• A00-B99 — Chapter 1: Certain Infectious and Parasitic Diseases (A00-B99) (A00-B99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B15-B19 — Viral hepatitis[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Excludes1 notes

• K73 — Chronic hepatitis, not elsewhere classified[Excludes1](via B17.-): “viral hepatitis (chronic) (B15-B19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K75.2 — Nonspecific reactive hepatitis[Excludes1](via B17.-): “viral hepatitis (B15-B19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K75.3 — Granulomatous hepatitis, not elsewhere classified[Excludes1](via B17.-): “viral hepatitis (B15-B19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K75.9 — Inflammatory liver disease, unspecified[Excludes1](via B17.-): “viral hepatitis (B15-B19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes2 notes (11)

• K70 — Alcoholic liver disease[Excludes2](via B17.-): “viral hepatitis (B15-B19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K70-K77 — Diseases of liver (K70-K77)[Excludes2](via B17.-): “viral hepatitis (B15-B19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K71 — Toxic liver disease[Excludes2](via B17.-): “viral hepatitis (B15-B19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K72 — Hepatic failure, not elsewhere classified[Excludes2](via B17.-): “viral hepatitis with hepatic coma (B15-B19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K73 — Chronic hepatitis, not elsewhere classified[Excludes2](via B17.-): “viral hepatitis (B15-B19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K74 — Fibrosis and cirrhosis of liver[Excludes2](via B17.-): “viral hepatitis (B15-B19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K75 — Other inflammatory liver diseases[Excludes2](via B17.-): “viral hepatitis (B15-B19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K75.0 — Abscess of liver[Excludes2]: “acute or subacute hepatitis NOS (B17.9)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• and 3 more

Referenced by Code First instructions

• H67 — Otitis media in diseases classified elsewhere[Code First](via B17.-): “viral disease NEC (B00-B34)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• M02 — Postinfective and reactive arthropathies[Code First](via B17.-): “viral hepatitis (B15-B19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Code Also instructions

• K74 — Fibrosis and cirrhosis of liver[Code Also](via B17.-): “, if applicable, viral hepatitis (acute) (chronic) (B15-B19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• INF007 — Hepatitis[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)
• INF008 — Viral infection[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 441 — DISORDERS OF LIVER EXCEPT MALIGNANCY, CIRRHOSIS OR ALCOHOLIC HEPATITIS WITH MCC[MS-DRG]: “DISORDERS OF LIVER EXCEPT MALIGNANCY, CIRRHOSIS OR ALCOHOLIC HEPATITIS WITH MCC (MDC 07)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 442 — DISORDERS OF LIVER EXCEPT MALIGNANCY, CIRRHOSIS OR ALCOHOLIC HEPATITIS WITH CC[MS-DRG]: “DISORDERS OF LIVER EXCEPT MALIGNANCY, CIRRHOSIS OR ALCOHOLIC HEPATITIS WITH CC (MDC 07)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 443 — DISORDERS OF LIVER EXCEPT MALIGNANCY, CIRRHOSIS OR ALCOHOLIC HEPATITIS WITHOUT CC/MCC[MS-DRG]: “DISORDERS OF LIVER EXCEPT MALIGNANCY, CIRRHOSIS OR ALCOHOLIC HEPATITIS WITHOUT CC/MCC (MDC 07)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 791 — PREMATURITY WITH MAJOR PROBLEMS[MS-DRG]: “PREMATURITY WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS[MS-DRG]: “FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 07 — Diseases and Disorders of the Hepatobiliary System and Pancreas[MDC crossing]: “Diseases and Disorders of the Hepatobiliary System and Pancreas — 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. 2,481 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026
• MDC 15 — Newborns and Other Neonates with Conditions Originating in Perinatal Period[MDC crossing]: “Newborns and Other Neonates with Conditions Originating in Perinatal Period — 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 · FY2026

Index entries

• Hepatitis, acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Hepatitis, acute, infectious[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Hepatitis, acute, viral (see also, Hepatitis, viral)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Hepatitis, infectious, infective, acute (subacute)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Hepatitis, viral, virus, acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

• B17 — Other acute viral hepatitis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B17.0 — Acute delta-(super) infection of hepatitis B carrier[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B17.1 — Acute hepatitis C[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B17.10 — Acute hepatitis C without hepatic coma[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B17.11 — Acute hepatitis C with hepatic coma[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B17.2 — Acute hepatitis E[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• B17.8 — Other specified acute viral hepatitis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Change history

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

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 FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 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 — v43 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 structured 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 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.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to B17.9 in its code family, with their registry titles.

• B17 — Other acute viral hepatitis
• B17.0 — Acute delta-(super) infection of hepatitis B carrier
• B17.1 — Acute hepatitis C
• B17.10 — Acute hepatitis C without hepatic coma
• B17.11 — Acute hepatitis C with hepatic coma
• B17.2 — Acute hepatitis E
• B17.8 — Other specified acute viral hepatitis

View all codes in the B17 family