ICD-10 Code K59 – Other functional intestinal disorders (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K59 – Other functional intestinal disorders
What it is
K59 is the ICD-10-CM category for functional intestinal disorders that affect bowel movement or stool passage without a clear structural cause. Use it when documentation describes a bowel function problem, but not a more specific diagnosis.
Clinical signs
Clinical features vary; refer to documentation. Common findings include constipation, altered bowel habits, abdominal discomfort, or difficulty passing stool when no obstructive lesion is identified.
When to use this code
Use K59 when the provider documents a functional disorder of the intestine and does not identify a more specific code. It may apply to chronic constipation, fecal retention, or other nonobstructive bowel dysfunctions. If the note names a specific subtype, code that diagnosis instead.
Do not use for
Do not use K59 for intestinal obstruction, inflammatory bowel disease, or symptoms explained by another diagnosed condition. Check documentation if the bowel problem is secondary to medication, surgery, or a neurological disorder.
Coding tip
Code the most specific documented bowel disorder first; use K59 only when the record supports a functional intestinal diagnosis and no better code is available.