ICD-10 Code K59.9 – Functional intestinal disorder, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K59.9 – Functional intestinal disorder, unspecified
What it is
K59.9 identifies a functional intestinal disorder when the specific bowel problem is not documented. It is used for intestinal dysfunction without a more precise diagnosis.
Clinical signs
Clinical features vary; refer to documentation. Patients may report altered bowel habits, abdominal discomfort, bloating, or nonspecific intestinal symptoms without an established structural cause.
When to use this code
Use this code when the record states a functional intestinal disorder but does not name a more specific condition. It also fits when the provider documents nonspecific bowel dysfunction and further detail is unavailable.
Choose the most specific code available if the chart identifies a named disorder such as constipation, diarrhea, or irritable bowel syndrome. Check documentation before defaulting to K59.9.
Do not use for
Do not use K59.9 when the condition is better described by a specific intestinal disorder code. Avoid it for clearly documented constipation, diarrhea, or other defined gastrointestinal diagnoses.
Coding tip
If the note is vague, query for the exact bowel diagnosis before assigning K59.9.