Acute appendicitis
In Diseases of appendix (K35-K38), chapter 11: Diseases of the Digestive System
13 billable codes under K35: 5 are an MCC, 8 are a CC; none map to an HCC.A CC or MCC (major CC) is a secondary diagnosis that raises the MS-DRG payment.
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Official coding guidelines
From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.
There are no chapter-specific rules for Chapter 11 yet, so the general rules in Section I.B apply.
All codes under K35
K35 can't be used on a claim. Pick a billable code below; grey headings group them.
- K35.2Acute appendicitis with generalized peritonitis
- K35.20Acute appendicitis with generalized peritonitis, without abscess
- K35.200Acute appendicitis with generalized peritonitis, without perforation or abscess
- K35.201Acute appendicitis with generalized peritonitis, with perforation, without abscess
- K35.209Acute appendicitis with generalized peritonitis, without abscess, unspecified as to perforation
- K35.21Acute appendicitis with generalized peritonitis, with abscess
- K35.210Acute appendicitis with generalized peritonitis, without perforation, with abscess
- K35.211Acute appendicitis with generalized peritonitis, with perforation and abscess
- K35.219Acute appendicitis with generalized peritonitis, with abscess, unspecified as to perforation
- K35.3Acute appendicitis with localized peritonitis
- K35.30Acute appendicitis with localized peritonitis, without perforation or gangrene
- K35.31Acute appendicitis with localized peritonitis and gangrene, without perforation
- K35.32Acute appendicitis with perforation, localized peritonitis, and gangrene, without abscess
- K35.33Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess
- K35.8Other and unspecified acute appendicitis
- K35.80Unspecified acute appendicitis
- K35.89Other acute appendicitis
- K35.890Other acute appendicitis without perforation or gangrene
- K35.891Other acute appendicitis without perforation, with gangrene
K35 MS-DRGs
As the principal diagnosis, the billable codes under K35 group to MS-DRG 371, 372, 373, 393, 394, or 395 (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.
- DRG 371 Major Gastrointestinal Disorders and Peritoneal Infections with MCC (12 of 13 codes)
- DRG 372 Major Gastrointestinal Disorders and Peritoneal Infections with CC (12 of 13 codes)
- DRG 373 Major Gastrointestinal Disorders and Peritoneal Infections without CC/MCC (12 of 13 codes)
- DRG 393 Other Digestive System Diagnoses with MCC (1 of 13 codes)
- DRG 394 Other Digestive System Diagnoses with CC (1 of 13 codes)
- DRG 395 Other Digestive System Diagnoses without CC/MCC (1 of 13 codes)
Other codes that refer to K35
Notes on these codes point to K35.
- K65 Excludes1: peritonitis with or following appendicitis (K35.-)
About the condition
Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.
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. If the blockage is not treated, the appendix can burst and spread infection into the abdomen. This causes a condition called peritonitis.
Read more about appendicitis on MedlinePlusCode history
Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.