ICD-10 Code K35.33 – Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K35.33 – Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess
What it is
This code identifies acute appendicitis that has ruptured, caused localized peritonitis, and developed gangrene with an abscess. Use it when the documentation clearly shows all of these complications together.
Clinical signs
Typical findings include right lower quadrant pain, abdominal tenderness, and evidence of perforation or localized infection around the appendix. Clinical features vary; refer to documentation for gangrene, abscess, or peritoneal involvement.
When to use this code
Use K35.33 when the provider documents acute appendicitis with perforation, localized peritonitis, gangrene, and abscess in the same episode. It is appropriate when imaging, operative findings, or pathology support these complications. If the record does not confirm all elements, check documentation before assigning this code.
Do not use for
Do not use this code for uncomplicated appendicitis, appendicitis without abscess, or perforation without localized peritonitis and gangrene. If the exact complication set is not stated, choose the more specific documented code or check documentation.
Coding tip
Verify that perforation, localized peritonitis, gangrene, and abscess are all documented before coding K35.33.