Version 2024

2024 ICD-10-CM Diagnosis Code K35

Acute appendicitis

ICD-10-CM Code:
ICD-10 Code for:
Acute appendicitis
Is Billable?
Not Valid for Submission
Code Navigator:

Code Classification

  • Diseases of the digestive system
    • Diseases of appendix
      • Acute appendicitis

K35 is a non-specific and non-billable diagnosis code code, consider using a code with a higher level of specificity for a diagnosis of acute appendicitis. The code is not specific and is NOT valid for the year 2024 for the submission of HIPAA-covered transactions. Category or Header define the heading of a category of codes that may be further subdivided by the use of 4th, 5th, 6th or 7th characters.

Specific Coding Applicable to Acute appendicitis

Non-specific codes like K35 require more digits to indicate the appropriate level of specificity. Consider using any of the following ICD-10-CM codes with a higher level of specificity when coding for acute appendicitis:

  • K35.2 for Acute appendicitis with generalized peritonitis - NON-BILLABLE CODE

  • K35.20 for Acute appendicitis with generalized peritonitis, without abscess - NON-BILLABLE CODE

  • K35.21 for Acute appendicitis with generalized peritonitis, with abscess - NON-BILLABLE CODE

  • K35.3 for Acute appendicitis with localized peritonitis - NON-BILLABLE CODE

  • Use K35.30 for Acute appendicitis with localized peritonitis, without perforation or gangrene - BILLABLE CODE

  • Use K35.31 for Acute appendicitis with localized peritonitis and gangrene, without perforation - BILLABLE CODE

  • Use K35.32 for Acute appendicitis with perforation, localized peritonitis, and gangrene, without abscess - BILLABLE CODE

  • Use K35.33 for Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess - BILLABLE CODE

  • K35.8 for Other and unspecified acute appendicitis - NON-BILLABLE CODE

  • Use K35.80 for Unspecified acute appendicitis - BILLABLE CODE

  • K35.89 for Other acute appendicitis - NON-BILLABLE CODE

Patient Education


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.

The main symptom is pain in the abdomen, often on the right side. It is usually sudden and gets worse over time. Other symptoms may include:

  • Swelling in the abdomen
  • Loss of appetite
  • Nausea and vomiting
  • Constipation or diarrhea
  • Inability to pass gas
  • Low fever

Not everyone with appendicitis has all these symptoms.

Appendicitis is a medical emergency. Treatment almost always involves removing the appendix. Anyone can get appendicitis, but it is more common among people 10 to 30 years old.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases

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Code History

  • FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
  • FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
  • FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.