ICD-10-CM 2027 diagnosis code

K35.89Other acute appendicitis

Not billable — use a more specific code

K35.89 is a header code, so it can't be reported by itself. Choose one of the 2 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 K35.89

K35.89 is the ICD-10-CM diagnosis code for other acute appendicitis. 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 2 subcodes must be used instead.

Within K35.8, choose K35.89 (Other acute appendicitis) only when documentation doesn't support a more specific option: unspecified acute appendicitis (K35.80).

To report this condition, pick the subcode that matches the documentation: K35.890 (without perforation or gangrene) and K35.891 (without perforation, with gangrene).

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 540.9 (acute appendicitis without mention of peritonitis).

Specific codes under K35.89

Notes that apply from higher levels

Instructions written at a parent level also apply to K35.89.

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

ICD-9-CM equivalent

Converter →

540.9Acute appendicitis without mention of peritonitisapproximate

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

Code history

2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
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 K35.89

Is K35.89 billable?: No. K35.89 is a header code. Report one of its more specific subcodes instead.
What is the ICD-9 code for K35.89?: The CMS General Equivalence Mappings map K35.89 to ICD-9-CM 540.9.