ICD-10 Code K35.210 – Acute appendicitis with generalized peritonitis, without perforation, with abscess (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K35.210 – Acute appendicitis with generalized peritonitis, without perforation, with abscess
What it is
K35.210 identifies acute appendicitis complicated by generalized peritonitis and an abscess, but without documented perforation. Use it when the record clearly links the inflamed appendix to diffuse peritoneal infection and a localized abscess.
Clinical signs
Typical findings include acute abdominal pain, guarding, rebound tenderness, and signs of peritoneal irritation. Imaging or operative documentation may show an appendiceal abscess with generalized peritonitis; clinical features vary, so refer to documentation.
When to use this code
Assign this code when the provider documents acute appendicitis with generalized peritonitis and an abscess, and there is no statement of perforation. Use it for operative, imaging, or discharge documentation that supports both the abscess and diffuse peritoneal involvement.
If the note only says appendicitis with abscess, check whether generalized peritonitis is also documented. Do not assume perforation unless the record states it.
Do not use for
Do not use this code for appendicitis without generalized peritonitis, or when perforation is documented. If the chart is unclear about abscess or peritoneal spread, check documentation.
Coding tip
Code only when both generalized peritonitis and abscess are documented together, and verify that perforation is explicitly absent.