J98.51 ICD-10-CM Code: Mediastinitis

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for J98.51 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 J98.51 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for J98.51

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

Before you code J98.51

1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with J98.51. 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 documentation support a condition named in J98.51’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.

   ReviewP28.4, P28.3

2. Is the underlying (etiologic) condition the Code First note names documented?
   Yes → Sequence the underlying condition first, then J98.51.
   No → Continue; do not add an underlying condition the record does not document.

   ReviewT81

Consider J98.51. Then work the Use Additional Code note, and 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).

The underlying (etiologic) condition

Named in the Code First note; sequenced before this code when documented (Guidelines I.A.13).

The conditions the Use Additional Code note names

Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

• Excludes1 — check before selecting J98.51(2 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with J98.51: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareP28.4, P28.3

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

• Excludes2 — not part of J98.51(3 notes)

  Coding workflow: The conditions named in this note are not included in J98.51. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  CompareJ85.3, R06.81, G47.3

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

• Code First — sequencing check(1 note)

  Coding workflow: Check whether the underlying or etiologic condition the note names is documented. When it is, sequence it before J98.51. Do not add an underlying condition the record does not document.

  ReviewT81

  See the official tabular notes · Guidelines I.A.13

• Use Additional Code — after identifying J98.51(7 notes)

  Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with J98.51 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

  ReviewZ77.22, P96.81, Z87.891, Z57.31, F17, Z72.0

  See the official tabular notes · Guidelines I.A.13

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 (2)

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.

• Infection, infected, infective (opportunistic), mediastinum
• Mediastinitis (acute) (chronic)

Don’t confuse J98.51 with…

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

The codes most likely to be picked instead of J98.51 — 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.

• P28.4— 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 newborn apnea moves the case to P28.4; the two are not reported together unless documented as unrelated.

  Full comparison: J98.51 vs P28.4 →

• P28.3— 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 newborn sleep apnea moves the case to P28.3; the two are not reported together unless documented as unrelated.

  Full comparison: J98.51 vs P28.3 →

• J85.3— 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 abscess of mediastinum adds J85.3; it is not part of this code and both may be reported when both are documented.

  Full comparison: J98.51 vs J85.3 →

• R06.81— 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 apnea NOS adds R06.81; it is not part of this code and both may be reported when both are documented.

  Full comparison: J98.51 vs R06.81 →

• G47.3— 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 sleep apnea adds G47.3; it is not part of this code and both may be reported when both are documented.

  Full comparison: J98.51 vs G47.3 →

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.

Decision Points

The directives on this code's own record, as a pre-claim checklist.

1. Sequencing: 1 Code First instruction — the underlying condition is sequenced before this code when present. See the Code First notes
2. 7 Use Additional Code instructions — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
3. 2 Excludes1 entries — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes
4. 3 Excludes2 entries — those conditions are not part of this code and may be reported additionally when documented. See the Excludes2 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

Verify Before Coding

• MCC 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

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: MCC — Major 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 1 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 5 MS-DRGs: DRG 177 (MDC 04), DRG 178 (MDC 04), DRG 179 (MDC 04), 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):RSP015 — Mediastinal disorders (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 category (CCSR)

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

J85.3 — Abscess of mediastinum, J98.5 — Diseases of mediastinum, not elsewhere classified, J98.59 — Other diseases of mediastinum, not elsewhere classified

Same Index main term, other category

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

A15.8 — Other respiratory tuberculosis (tuberculous), A52.73 — Symptomatic late syphilis of other respiratory organs (syphilitic)

Contextual Map

Every relationship of J98.51 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 J98.51 with this related code in Claim Check

Hierarchy

• J00-J99 — Chapter 10: Diseases of the Respiratory System (J00-J99) (J00-J99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Code First

• T81 — Complications of procedures, not elsewhere classified[Code First]: “underlying condition, if applicable, such as postoperative mediastinitis (T81.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• RSP015 — Mediastinal disorders[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• MCC — Major Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (MCC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 177 — RESPIRATORY INFECTIONS AND INFLAMMATIONS WITH MCC[MS-DRG]: “RESPIRATORY INFECTIONS AND INFLAMMATIONS WITH MCC (MDC 04)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 178 — RESPIRATORY INFECTIONS AND INFLAMMATIONS WITH CC[MS-DRG]: “RESPIRATORY INFECTIONS AND INFLAMMATIONS WITH CC (MDC 04)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 179 — RESPIRATORY INFECTIONS AND INFLAMMATIONS WITHOUT CC/MCC[MS-DRG]: “RESPIRATORY INFECTIONS AND INFLAMMATIONS WITHOUT CC/MCC (MDC 04)”— 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 04 — Diseases and Disorders of the Respiratory System[MDC crossing]: “Diseases and Disorders of the Respiratory System — 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. 3,998 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

• Infection, infected, infective (opportunistic), mediastinum[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Mediastinitis (acute) (chronic)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (15)

• J98 — Other respiratory disorders[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• J98.0 — Diseases of bronchus, not elsewhere classified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• J98.01 — Acute bronchospasm[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• J98.09 — Other diseases of bronchus, not elsewhere classified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• J98.1 — Pulmonary collapse[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• J98.11 — Atelectasis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• J98.19 — Other pulmonary collapse[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• J98.2 — Interstitial emphysema[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 7 more

Change history

• FY2017 — Added to the code set[Change history]— CMS release files (code change ledger) · icd10cm-fy2017

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 J98.51 in its code family, with their registry titles.

• J98.11 — Atelectasis
• J98.19 — Other pulmonary collapse
• J98.2 — Interstitial emphysema
• J98.3 — Compensatory emphysema
• J98.4 — Other disorders of lung
• J98.5 — Diseases of mediastinum, not elsewhere classified
• J98.59 — Other diseases of mediastinum, not elsewhere classified
• J98.6 — Disorders of diaphragm
• J98.8 — Other specified respiratory disorders
• J98.9 — Respiratory disorder, unspecified

View all codes in the J98 family