ICD-10 Code K51.90 – Ulcerative colitis, unspecified, without complications (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K51.90 – Ulcerative colitis, unspecified, without complications
What it is
K51.90 identifies ulcerative colitis when the provider documents the disease but does not specify the site or a complication. It is used for a chronic inflammatory bowel disease affecting the colon.
Clinical signs
Typical findings include recurrent diarrhea, rectal bleeding, abdominal pain, and urgency. Clinical features vary; refer to documentation for confirmed extent and whether complications are present.
When to use this code
Use K51.90 when the record states ulcerative colitis and does not describe a more specific type, location, or associated complication. It fits encounters for ongoing management, evaluation, or follow-up when the diagnosis remains nonspecific.
If the note later specifies rectal involvement, pancolitis, or a complication, you should code that more detailed option instead. Check documentation before assigning the unspecified code.
Do not use for
Do not use this code for Crohn disease, infectious colitis, or ulcerative colitis with complications. Also avoid it when the chart clearly identifies a more specific ulcerative colitis subtype.
Coding tip
Code K51.90 only when the provider’s documentation supports ulcerative colitis but leaves the type and complication status unspecified.