ICD-10 Code K38.3 – Fistula of appendix (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K38.3 – Fistula of appendix
What it is
K38.3 identifies an abnormal fistulous connection involving the appendix. It means the appendix has formed an unwanted passage to another structure or the skin, based on the documented diagnosis.
Clinical signs
Clinical features vary; refer to documentation. Findings may include persistent abdominal symptoms, localized drainage, or evidence of an abnormal appendix-related tract on imaging or surgery.
When to use this code
Use K38.3 when the provider documents a fistula of the appendix as the confirmed diagnosis. This may appear in operative reports, imaging interpretations, or discharge summaries. Code it when the record clearly identifies the appendix as the fistula source.
Do not use for
Do not use this code for general appendicitis, perforation without a fistula, or fistulas arising from another organ. Check documentation if the record only says “abdominal fistula” without naming the appendix.
Coding tip
Look for explicit wording such as “appendiceal fistula” or “fistula of appendix” before assigning K38.3.