ICD-10 Code K51 – Ulcerative Colitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K51 – Ulcerative colitis
What it is
K51 identifies ulcerative colitis, a chronic inflammatory disease of the colon and rectum. It is used when documentation states ulcerative colitis without a more specific site or complication.
Clinical signs
Typical findings include recurrent diarrhea, rectal bleeding, abdominal pain, and urgency. Clinical features vary; refer to documentation for disease extent, severity, and any complications.
When to use this code
Use K51 when the provider documents ulcerative colitis and does not specify a more detailed subcategory. It also applies when the record confirms inflammatory colitis consistent with ulcerative colitis. Code more specific K51.- options when the site, severity, or complication is documented.
Do not use for
Do not use K51 for Crohn disease, infectious colitis, ischemic colitis, or irritable bowel syndrome. Check documentation if the diagnosis is uncertain or another colitis type is named.
Coding tip
Always look for laterality, extent, and complications in the note before settling on the unspecified code.