ICD-10 Code K31.6 – Fistula of stomach and duodenum (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K31.6 – Fistula of stomach and duodenum
What it is
K31.6 identifies an abnormal passage between the stomach and duodenum. Use it when documentation states a fistula connecting these two upper gastrointestinal structures.
Clinical signs
Findings may include persistent upper abdominal symptoms, abnormal gastrointestinal drainage, or imaging evidence of an abnormal tract. Clinical features vary; refer to documentation.
When to use this code
Use K31.6 when the provider documents a fistula between the stomach and duodenum, including postoperative or disease-related cases. Code it from confirmed clinical, endoscopic, or radiologic documentation. If the record only mentions suspected fistula, check documentation before assigning the code.
Do not use for
Do not use this code for fistulas involving other organs or for a generic gastrointestinal fistula without stomach-duodenum involvement. Check documentation if the anatomic site is unclear.
Coding tip
Always verify the exact fistula location and whether the condition is confirmed before coding K31.6.