ICD-10 Code K35.30 – Acute appendicitis with localized peritonitis, without perforation or gangrene (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K35.30 – Acute appendicitis with localized peritonitis, without perforation or gangrene
What it is
K35.30 identifies acute appendicitis complicated by localized peritonitis, but without perforation or gangrene. Use it when the appendix is inflamed and the surrounding peritoneum is involved in a limited area.
Clinical signs
Typical findings include right lower quadrant abdominal pain, tenderness, and localized guarding or rebound. Imaging or operative documentation may confirm appendiceal inflammation with localized peritoneal irritation; clinical features vary, so refer to documentation.
When to use this code
Use K35.30 when the record clearly states acute appendicitis with localized peritonitis and specifically notes no perforation and no gangrene. It is appropriate for confirmed cases documented by the surgeon, radiologist, or discharge summary.
If the chart mentions peritoneal inflammation around the appendix but does not describe rupture or necrosis, this code may fit. Check documentation when the severity or complication status is unclear.
Do not use for
Do not use this code if the appendicitis is perforated, gangrenous, or both. Also avoid it when the record only says uncomplicated appendicitis or generalized peritonitis.
Coding tip
Match the code to explicit wording in the note; “localized peritonitis” alone is not enough if perforation or gangrene is documented elsewhere.