ICD-10 Code K35.211 – Acute appendicitis with generalized peritonitis, with perforation and abscess (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K35.211 – Acute appendicitis with generalized peritonitis, with perforation and abscess
What it is
This code identifies acute appendicitis that has ruptured, causing generalized peritonitis and an abscess. Use it when documentation shows both perforation and diffuse abdominal infection.
Clinical signs
Typical findings include acute right lower quadrant pain, abdominal guarding, rebound tenderness, and signs of generalized peritoneal irritation. Clinical features vary; refer to documentation.
When to use this code
Use K35.211 when the record clearly documents acute appendicitis with perforation, generalized peritonitis, and an abscess. You may also use it when operative, imaging, or discharge documentation confirms these findings. Check documentation if the note only states perforation or localized peritonitis.
Do not use for
Do not use this code for uncomplicated appendicitis, localized peritonitis, or appendiceal abscess without generalized peritonitis. If the documentation is incomplete, check documentation.
Coding tip
Assign this code only when all three elements are documented: perforation, generalized peritonitis, and abscess.