ICD-10 Code K35.201 – Acute appendicitis with generalized peritonitis, with perforation, without abscess (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K35.201 – Acute appendicitis with generalized peritonitis, with perforation, without abscess
What it is
This code identifies acute appendicitis that has perforated and caused generalized peritonitis, but no abscess is documented. Use it when the appendix has ruptured and infection has spread throughout the peritoneal cavity.
Clinical signs
Typical findings include acute abdominal pain, rebound tenderness, guarding, and signs of diffuse peritoneal irritation. Clinical features vary; refer to documentation for perforation and the absence of abscess.
When to use this code
Use K35.201 when the provider documents acute appendicitis with generalized peritonitis and confirms perforation without abscess. This may appear in operative notes, imaging reports, or discharge summaries. If abscess is mentioned, check documentation before assigning this code.
Do not use for
Do not use this code for appendicitis without perforation, localized peritonitis, or appendiceal abscess. If the record does not clearly state generalized peritonitis and no abscess, check documentation.
Coding tip
Code only when both perforation and generalized peritonitis are documented, and verify that abscess is specifically ruled out.