ICD-10 Code K66 – Other disorders of peritoneum (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K66 – Other disorders of peritoneum
What it is
K66 covers disorders affecting the peritoneum that are not classified elsewhere. Use it when documentation identifies a peritoneal condition, but no more specific ICD-10-CM code applies.
Clinical signs
Clinical features vary; refer to documentation. Findings may include abdominal pain, distension, tenderness, or signs related to peritoneal inflammation, adhesion, or other peritoneal abnormality.
When to use this code
Use K66 when the record clearly describes a disorder of the peritoneum and the provider does not name a more specific diagnosis. It is appropriate for nonspecific or residual peritoneal conditions after review of the chart.
If the documentation names a defined condition with its own code, report that code instead. Check documentation for the exact peritoneal diagnosis and any related underlying cause.
Do not use for
Do not use K66 for generalized abdominal pain, peritonitis with a more specific code, or conditions outside the peritoneum. Do not assign it when the documentation supports a better-defined diagnosis.
Coding tip
Query for specificity if the note only says “peritoneal disorder” or “peritoneal abnormality.”