ICD-10 Code K59.8 – Other specified functional intestinal disorders (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K59.8 – Other specified functional intestinal disorders
What it is
K59.8 identifies functional intestinal disorders that do not fit a more specific ICD-10 category. Use it when the bowel problem is documented as functional and another code is not appropriate.
Clinical signs
Clinical features vary; refer to documentation. Records may describe altered bowel habits, abdominal discomfort, bloating, or constipation-like symptoms without a structural intestinal disease.
When to use this code
Use K59.8 when the provider specifically documents an other specified functional intestinal disorder and the note does not support a more exact K59 code. It may apply when symptoms are persistent but the diagnosis remains functional rather than organic. Check documentation if the chart is vague.
Do not use for
Do not use this code for constipation, irritable bowel syndrome, or intestinal obstruction when a more specific diagnosis is documented. If the cause is structural, inflammatory, or otherwise specified, choose the matching code.
Coding tip
Code only what the provider states; if “functional bowel disorder” is nonspecific, query for the exact diagnosis.