2026 ICD-10-CM Diagnosis Code K35.891Other acute appendicitis without perforation, with gangrene

ICD-10-CM Codes›K00–K95›K35-K38›K35

ICD-10-CM K35.891
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K35.891 is a billable ICD-10-CM diagnosis code for other acute appendicitis without perforation, with gangrene. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 371 through 373. Coders also document this condition as gangrenous appendicitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Appendicitis and other appendiceal conditions.

Code Identity

ICD-10-CM Code
K35.891
Billable Status
Yes — Valid for Submission
Code Describes
Other acute appendicitis without perforation, with gangrene
Short Description
Other acute appendicitis without perforation, with gangrene
Same as the full description in the CMS dataset.
Parent Code
K35.89
Other acute appendicitis

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK35-K38Diseases of appendix
CategoryK35Acute appendicitis
This CodeK35.891Other acute appendicitis without perforation, with gangrene

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Gangrenous appendicitis

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • (Acute) appendicitis with gangrene NOS

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Appendicitis(pneumococcal) (retrocecal)
      • with
        • gangrene
    • Appendicitis(pneumococcal) (retrocecal)
      • acute (catarrhal) (fulminating) (obstructive) (retrocecal) (suppurative)
        • with
          • gangrene
    • Appendicitis(pneumococcal) (retrocecal)
      • acute (catarrhal) (fulminating) (obstructive) (retrocecal) (suppurative)
        • specified NEC
          • with gangrene

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR DIG009
Appendicitis and other appendiceal conditions
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Appendicitis

The appendix is a small, tube-like organ attached to the first part of the large intestine. It is located in the lower right part of the abdomen. It has no known function. A blockage inside of the appendix causes appendicitis. The blockage leads to increased pressure, problems with blood flow, and inflammation.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Code History & ChangesHistory

Replacement K35.891 replaces the following previously assigned code(s):

  • K35.89 - Other acute appendicitis
FY 2019AddedAdded to the ICD-10-CM code setEffective October 1, 2018.
FY 2020–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About K35.891Overview

Is K35.891 (Other acute appendicitis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other acute appendicitis without perforation, with gangrene on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K35.891 group to?

When other acute appendicitis without perforation, with gangrene is the principal diagnosis on an inpatient stay, it groups to MS-DRG 371, 372, 373, with relative weights from 0.7274 to 1.7731 depending on complications. Higher weights mean higher Medicare reimbursement.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.