ICD-10-CM 2027 diagnosis code

K35.8Other and unspecified acute appendicitis

Not billable — use a more specific code

K35.8 is a header code, so it can't be reported by itself. Choose one of the 2 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About K35.8

K35.8 is the ICD-10-CM diagnosis code for other and unspecified 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, choose K35.8 (Other and unspecified acute appendicitis) only when documentation doesn't support a more specific option: with generalized peritonitis (K35.2) and with localized peritonitis (K35.3).

To report this condition, pick the subcode that matches the documentation: K35.80 (appendicitis) and K35.89 (appendicitis).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under K35.8

Notes that apply from higher levels

Instructions written at a parent level also apply to K35.8.

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

Code history

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2027

FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
No changes since FY2016.

Common questions about K35.8

Is K35.8 billable?: No. K35.8 is a header code. Report one of its more specific subcodes instead.