ICD-10 Code K51.91 – Ulcerative colitis, unspecified, with complications (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K51.91 – Ulcerative colitis, unspecified, with complications
What it is
K51.91 identifies ulcerative colitis when the site or subtype is not specified and the record documents a complication. Use it for inflammatory bowel disease limited to the colon when complications are present.
Clinical signs
Clinical features vary; refer to documentation. Common findings include chronic diarrhea, rectal bleeding, abdominal pain, urgency, and evidence of a complication such as anemia, dehydration, or other documented colitis-related problems.
When to use this code
Use this code when the provider documents ulcerative colitis without further specification and also notes a complication. It is appropriate when the chart clearly links the complication to the colitis. If the complication is not documented, check documentation before assigning this code.
Do not use for
Do not use K51.91 for ulcerative colitis without complications, or when the diagnosis is a more specific ulcerative colitis code. Do not use it if the record does not support a complication or if documentation is unclear.
Coding tip
Confirm both the unspecified ulcerative colitis diagnosis and the documented complication before coding K51.91.