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K35.210 ICD-10-CM Code: Acute appendicitis with generalized peritonitis, without perforation, with abscess

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

Coding at a Glance

Tabular directives
1 inclusion term

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; the Instructions section marks which is which.

IncludesWhat this code covers
  • (Acute) appendicitis with generalized peritonitis without rupture or perforation of appendix, with abscess

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 371 — MAJOR GASTROINTESTINAL DISORDERS AND PERITONEAL INFECTIONS WITH MCC (MDC 06)
  • MS-DRG 372 — MAJOR GASTROINTESTINAL DISORDERS AND PERITONEAL INFECTIONS WITH CC (MDC 06)
  • MS-DRG 373 — MAJOR GASTROINTESTINAL DISORDERS AND PERITONEAL INFECTIONS WITHOUT CC/MCC (MDC 06)

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.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for K35.210 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

Inclusion Terms

Alternative terms the tabular list files under this code.

  • (Acute) appendicitis with generalized peritonitis without rupture or perforation of appendix, with abscess

Don’t confuse K35.210 with…

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

The codes most likely to be picked instead of K35.210 — 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.

  • K35.219— Specificity relationship (Review)

    Overlapping diagnoses in the same category.

    Overlapping codes in the same category — the documentation decides which is the more specific fit.

    What moves you there: A record that documents no more than “Acute appendicitis with generalized peritonitis, with abscess, unspecified as to perforation” takes K35.219; specificity in the record moves it back here.

    Full comparison: K35.210 vs K35.219 →

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

Acute appendicitis with generalized peritonitis, without perforation, with abscess is a billable ICD-10-CM diagnosis code (K35.210).

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

Official Coding Guidelines

No excerpt in the ICD-10-CM Official Guidelines names this code specifically. Its chapter carries only this chapter-wide note:

Chapter 11: Diseases of the Digestive System (K00-K95)

Reserved for future guideline expansion

Verify Before Coding

  • MCC 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 K35.210 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 3 Excludes1 notes: K37 — Unspecified appendicitis (via K35.2.-), K65 — Peritonitis (via K35.-), K65 — Peritonitis (via K35.2.-).

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

Referenced by 1 Excludes2 note: K63.1 — Perforation of intestine (nontraumatic) (via K35.2.-).

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

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 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 24 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 3 MS-DRGs: DRG 371 (MDC 06), DRG 372 (MDC 06), DRG 373 (MDC 06).

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

Clinical classification (AHRQ CCSR):DIG009 — Appendicitis and other appendiceal conditions (default); DIG016 — Peritonitis and intra-abdominal abscess.

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 MCC — 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.

K31.89 — Other diseases of stomach and duodenum, K31.9 — Disease of stomach and duodenum, unspecified, K35.200 — Acute appendicitis with generalized peritonitis, without perforation or abscess, K35.201 — Acute appendicitis with generalized peritonitis, with perforation, without abscess, K35.209 — Acute appendicitis with generalized peritonitis, without abscess, unspecified as to perforation, K35.211 — Acute appendicitis with generalized peritonitis, with perforation and abscess, K35.219 — Acute appendicitis with generalized peritonitis, with abscess, unspecified as to perforation, K35.30 — Acute appendicitis with localized peritonitis, without perforation or gangrene, K35.31 — Acute appendicitis with localized peritonitis and gangrene, without perforation, K35.32 — Acute appendicitis with perforation, localized peritonitis, and gangrene, without abscess, K35.33 — Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess, K35.80 — Unspecified acute appendicitis, K35.890 — Other acute appendicitis without perforation or gangrene, K35.891 — Other acute appendicitis without perforation, with gangrene, K36 — Other appendicitis, K37 — Unspecified appendicitis, K38.0 — Hyperplasia of appendix, K38.1 — Appendicular concretions, K38.2 — Diverticulum of appendix, K38.3 — Fistula of appendix, +3 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (Appendicitis and other appendiceal conditions, Peritonitis and intra-abdominal abscess).

A18.31 — Tuberculous peritonitis, A54.85 — Gonococcal peritonitis, A74.81 — Chlamydial peritonitis, K35.2 — Acute appendicitis with generalized peritonitis, K35.20 — Acute appendicitis with generalized peritonitis, without abscess, K35.200 — Acute appendicitis with generalized peritonitis, without perforation or abscess, K35.201 — Acute appendicitis with generalized peritonitis, with perforation, without abscess, K35.209 — Acute appendicitis with generalized peritonitis, without abscess, unspecified as to perforation, K35.21 — Acute appendicitis with generalized peritonitis, with abscess, K35.211 — Acute appendicitis with generalized peritonitis, with perforation and abscess, K35.219 — Acute appendicitis with generalized peritonitis, with abscess, unspecified as to perforation, K35.3 — Acute appendicitis with localized peritonitis, K35.30 — Acute appendicitis with localized peritonitis, without perforation or gangrene, K35.31 — Acute appendicitis with localized peritonitis and gangrene, without perforation, K35.32 — Acute appendicitis with perforation, localized peritonitis, and gangrene, without abscess, K35.33 — Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess, K35.80 — Unspecified acute appendicitis, K35.89 — Other acute appendicitis, K35.890 — Other acute appendicitis without perforation or gangrene, K35.891 — Other acute appendicitis without perforation, with gangrene, +44 more

Same Index main term, other category

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

A06.89 — Other amebic infections (amebic), A18.32 — Tuberculous enteritis (tuberculous), K36 — Other appendicitis (healed), K37 — Unspecified appendicitis

Contextual Map

Every relationship of K35.210 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 K35.210 with these 3 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

  • K37 — Unspecified appendicitis[Excludes1](via K35.2.-): “unspecified appendicitis with peritonitis (K35.2-, K35.3-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2027
  • K65 — Peritonitis[Excludes1](via K35.-): “peritonitis with or following appendicitis (K35.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2027
  • K65 — Peritonitis[Excludes1](via K35.2.-): “acute appendicitis with generalized peritonitis (K35.2-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2027

Referenced by Excludes2 notes

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 06 — Diseases and Disorders of the Digestive System[MDC crossing]: “Diseases and Disorders of the Digestive 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. 5,748 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries

  • Appendicitis (pneumococcal) (retrocecal), acute (catarrhal) (fulminating) (obstructive) (retrocecal) (suppurative), with, peritonitis NEC, generalized, with, abscess, without perforation or rupture[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Appendicitis (pneumococcal) (retrocecal), with, peritonitis NEC, generalized, with, abscess, without perforation or rupture[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027

Nearest codes (19)

Change history

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 (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.

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
Coding guidelines Official source data
ICD-10-CM Official Guidelines for Coding and Reporting (FY2027), quoted by section 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
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 20, 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. "K35.210 — Acute appendicitis with generalized peritonitis, without perforation, with abscess." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/k35.210-acute-appendicitis-with-generalized-peritonitis-without-perforation-with-abscess

Change history

  • FY2024 — October 1, 2023
    Added to the code set
    Acute appendicitis with generalized peritonitis, without perforation, with abscess
    FY2024 changes

Nearest Codes in This Family

Official ICD-10-CM classifications closest to K35.210 in its code family, with their registry titles.

View all codes in the K35 family