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ICD-10-CM 2027 diagnosis code

K35.3Acute appendicitis with localized peritonitis

Not billable — use a more specific code

K35.3 is a header code, so it can't be reported by itself. Choose one of the 4 more specific codes beneath it.

Code last changed in FY2019 (effective October 1, 2018). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About K35.3

K35.3 is the ICD-10-CM diagnosis code for acute appendicitis with localized peritonitis. It belongs to category K35 (acute appendicitis), block K35-K38 (diseases of appendix) and chapter 11 (diseases of the digestive system). It is a header code, so it can't be reported by itself; one of its 4 subcodes must be used instead.

Within K35 (acute appendicitis), K35.3 is specifically for acute appendicitis with localized peritonitis. Related codes cover with generalized peritonitis (K35.2) and other and unspecified acute appendicitis (K35.8).

To report this condition, pick the subcode that matches the documentation: K35.30 (without perforation or gangrene), K35.31 (and gangrene, without perforation), K35.32 (abscess) and K35.33 (abscess).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015, and changed in FY2019 (expanded into subcodes).

Before ICD-10, this condition was coded in ICD-9-CM as 540.1 (acute appendicitis with peritoneal abscess).

Specific codes under K35.3

Notes that apply from higher levels

Instructions written at a parent level also apply to K35.3.

Broader instructions also apply from Chapter 11: Diseases of the digestive system.

Codes whose notes reference K35.3

ICD-9-CM equivalent

Converter →
  • 540.1Acute appendicitis with peritoneal abscessapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • FY2019 (effective 10/1/2018): Expanded — no longer billable

Common questions about K35.3

Is K35.3 billable?

No. K35.3 is a header code. Report one of its more specific subcodes instead.

What is the ICD-9 code for K35.3?

The CMS General Equivalence Mappings map K35.3 to ICD-9-CM 540.1.