ICD-10 Code K51.9 – Ulcerative colitis, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K51.9 – Ulcerative colitis, unspecified
What it is
K51.9 identifies ulcerative colitis when the record confirms the diagnosis but does not specify the disease location or type. Use it for inflammatory bowel disease involving the colon when documentation remains nonspecific.
Clinical signs
Typical findings include chronic diarrhea, rectal bleeding, abdominal pain, and urgency. Clinical features vary; refer to documentation, especially when the note does not identify extent, severity, or complications.
When to use this code
Use K51.9 when the provider documents ulcerative colitis without further detail such as rectosigmoid, left-sided, or pancolitis disease. It also fits when the chart confirms ulcerative colitis but the available note is incomplete. You should code the unspecified option only when no more specific subtype is documented.
Do not use for
Do not use this code if the record specifies a more precise ulcerative colitis subtype or if Crohn disease, infectious colitis, or another cause is documented instead. Check documentation.
Coding tip
Query for disease location or complication details before defaulting to K51.9.