K35.31Acute appendicitis with localized peritonitis and gangrene, without perforation

K35.31 is the ICD-10-CM diagnosis code for acute appendicitis with localized peritonitis and gangrene, without perforation. It belongs to category K35 (acute appendicitis), block K35-K38 (diseases of appendix) and chapter 11 (diseases of the digestive system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within K35.3, choose K35.31 (and gangrene, without perforation) only when documentation doesn't support a more specific option: without perforation or gangrene (K35.30), perforation, localized peritonitis, and gangrene, without abscess (K35.32) and perforation, localized peritonitis, and gangrene, with abscess (K35.33).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 371 (Major Gastrointestinal Disorders and Peritoneal Infections with MCC, relative weight 1.7089), DRG 372 (Major Gastrointestinal Disorders and Peritoneal Infections with CC, relative weight 0.9964) and DRG 373 (Major Gastrointestinal Disorders and Peritoneal Infections without CC/MCC, relative weight 0.6941), in MDC 06 (Diseases and Disorders of the Digestive System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It was added in FY2019, effective October 1, 2018.