ICD10
ICD-10 Code K35.3: Acute appendicitis with localized peritonitis
Reviewed by HealthAssure Clinical TeamUpdated 26 May 2026
What is this code?
ICD-10 entries help standardize how diagnoses are organized for coding, reporting, analytics, and documentation. This code sits within the broader ICD-10 area for Diseases of the digestive system (K00-K95).
When is it used?
- May be used when a clinician documents acute appendicitis with localized peritonitis in a patient's medical record.
- May appear in hospital records, claims, referrals, and clinical documentation.
- This code may act more like a grouping or parent code, so a more specific child code may be used in final documentation when available.
What it does not mean
- A code alone does not explain severity, treatment plan, or outcome.
- A medical code should not be treated as a substitute for a doctor's diagnosis or advice.
- This entry may represent a broader category rather than the most specific billable code.
Code hierarchy
chapter
11Diseases of the digestive system (K00-K95)
block
K35-K38Diseases of appendix
category
K35Acute appendicitis
currentK35
Where you may see this code
You may see this entry in coding references, medical records, or claims workflows when a broader diagnosis category is being reviewed before a more specific code is chosen.
Related specialists
GastroenterologistGeneral Physician
Related codes
K35.30Acute appendicitis with localized peritonitis, without perforation or gangrenecodeK35.31Acute appendicitis with localized peritonitis and gangrene, without perforationcodeK35.32Acute appendicitis with perforation, localized peritonitis, and gangrene, without abscesscodeK35.33Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscesscode
Sibling codes
Mapped diagnoses and classifications
SNOMED_CT 62224002high
Abscess of appendix
Source: SNOMED International ICD-10 map
SNOMED_CT 266439004high
Acute appendicitis with appendix abscess
Source: SNOMED International ICD-10 map
SNOMED_CT 698294004high
Acute appendicitis with localised peritonitis
Source: SNOMED International ICD-10 map
SNOMED_CT 51036000high
Acute appendicitis with peritoneal abscess
Source: SNOMED International ICD-10 map
SNOMED_CT 196781001high
Acute appendicitis with peritonitis
Source: SNOMED International ICD-10 map
SNOMED_CT 64994000high
Acute fulminating appendicitis with perforation AND peritonitis
Source: SNOMED International ICD-10 map
Coding guidelines
Compatibility
Legacy code aligns to an official FY 2026 category. Frontend should resolve to the official category page and surface the billable child codes.
Legacy codes
K35.3
Replacement codes
K35.30 — Acute appendicitis with localized peritonitis, without perforation or gangreneK35.31 — Acute appendicitis with localized peritonitis and gangrene, without perforationK35.32 — Acute appendicitis with perforation, localized peritonitis, and gangrene, without abscessK35.33 — Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess
Common synonyms
Acute appendicitis with localized peritonitis
Frequently asked questions
About this content
This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.