Diseases of appendix (K35-K38) ICD-10-CM
The K35–K38 section covers diseases of appendix with 29 ICD-10-CM diagnosis codes, of which 21 are billable in fiscal year 2026. The section is organized into the 4 code ranges listed below.
Code Ranges in This Section 4 ranges · 29 codes
| Code Range | Title | Codes | Billable |
|---|---|---|---|
| K35 | Acute appendicitis (K35) | 20 | 13 |
| K36 | Other appendicitis (K36) | 1 | 1 |
| K37 | Unspecified appendicitis (K37) | 1 | 1 |
| K38 | Other diseases of appendix (K38) | 7 | 6 |
The info icon previews the code ranges inside each row and its instructional notations from the official Tabular List.
About the K35–K38 Code Range
The ICD-10 codes K35-K38 are used for diagnosing various diseases of the appendix, including different types of appendicitis and other appendix-related conditions. These codes capture both acute and chronic cases as well as complications like perforation, gangrene, abscess, and peritonitis.
Within this range, K35 primarily covers acute appendicitis, with specific codes distinguishing cases by complications such as generalized or localized peritonitis, with or without abscess or perforation. Common terms like "acute appendicitis with peritonitis" guide coders in selecting the exact code, for example, K35.2 for acute appendicitis with generalized peritonitis. Codes K36 and K37 address other and unspecified appendicitis types, including chronic or healed forms and atypical presentations. The K38 block covers non-appendicitis diseases of the appendix such as hyperplasia (lymphoid hyperplasia), diverticulum, fistula, and other specific disorders like mucocele of appendix. These codes help clinicians and coders accurately record appendix-related diagnoses to reflect the presence and severity of disease and related complications for treatment and billing purposes.
Questions About This Page
How many codes are in the K35-K38 range?
The K35-K38 range contains 29 ICD-10-CM diagnosis codes in FY 2026. 21 of them are billable, and the rest are category headers that organize the section.
What conditions does K35-K38 cover?
The range covers diseases of appendix. The code ranges listed above break it into groups of related conditions, and each one links to its own page with the full code list.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
