ICD-10-CM 2027 diagnosis code
K35.33Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess
K35.33 is a valid, billable ICD-10-CM code for acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.Short description: Ac appendicitis with perf, loc peritonitis, and gangr, wbscs
Code last changed in FY2023 (effective October 1, 2022). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About K35.33
K35.33 is the ICD-10-CM diagnosis code for acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess. 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 (acute appendicitis with localized peritonitis), K35.33 is specifically for acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess. Related codes cover without perforation or gangrene (K35.30), and gangrene, without perforation (K35.31) and perforation, localized peritonitis, and gangrene, without abscess (K35.32).
As a secondary diagnosis it is an MCC (major complication or comorbidity), which can move an inpatient stay into the highest-paying "with MCC" 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, and changed in FY2023.
Coding notes
- (Acute) appendicitis with (peritoneal) abscess NOS
- Ruptured appendix with localized peritonitis and abscess
Notes that apply from higher levels
Instructions written at a parent level also apply to K35.33.
Broader instructions also apply from Chapter 11: Diseases of the digestive system.
Alphabetic index entries
18 entriesTerms in the official ICD-10-CM index that lead to K35.33.
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic) › appendix
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic) › cecum
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic) › ileocecal
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic) › iliac (region) › fossa
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic) › periappendicular
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic) › pericecal
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic) › peritoneum, peritoneal (perforated) (ruptured) › with appendicitis
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic) › perityphlic
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic) › postcecal
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic) › subcecal
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic) › vermiform appendix
- Appendicitis (pneumococcal) (retrocecal) › with › peritoneal abscess
- Appendicitis (pneumococcal) (retrocecal) › with › peritonitis NEC
- Appendicitis (pneumococcal) (retrocecal) › with › peritonitis NEC › localized › with › perforation › and abscess
- Appendicitis (pneumococcal) (retrocecal) › acute (catarrhal) (fulminating) (obstructive) (retrocecal) (suppurative) › with › peritoneal abscess
- Appendicitis (pneumococcal) (retrocecal) › acute (catarrhal) (fulminating) (obstructive) (retrocecal) (suppurative) › with › peritonitis NEC
- Appendicitis (pneumococcal) (retrocecal) › acute (catarrhal) (fulminating) (obstructive) (retrocecal) (suppurative) › with › peritonitis NEC › localized › with › perforation › and abscess
- Rupture, ruptured › cecum (with peritonitis) › with peritoneal abscess
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2019 (effective 10/1/2018): Added
- FY2023 (effective 10/1/2022): Title revised — was “Acute appendicitis with perforation and localized peritonitis, with abscess”
Common questions about K35.33
Is K35.33 billable?
- Yes. K35.33 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can K35.33 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict K35.33 as a principal diagnosis.
Is K35.33 a CC or MCC?
- K35.33 is an MCC (major complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.
What DRG does K35.33 group to?
- K35.33 is used in the MS-DRG v44.0 logic for MS-DRG 371 (Major Gastrointestinal Disorders and Peritoneal Infections with MCC), MS-DRG 372 (Major Gastrointestinal Disorders and Peritoneal Infections with CC) and MS-DRG 373 (Major Gastrointestinal Disorders and Peritoneal Infections without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.