ICD-10 Code K51.51 – Left sided colitis with complications (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K51.51 – Left sided colitis with complications
What it is
K51.51 identifies left-sided ulcerative colitis with complications. It applies when inflammation involves the descending colon and related left colon segments, and the record documents a complication.
Clinical signs
Typical findings include chronic bloody diarrhea, abdominal cramping, urgency, and rectal bleeding. Clinical features vary; refer to documentation for the specific complication and extent of disease.
When to use this code
Use K51.51 when the provider documents left-sided colitis or left-sided ulcerative colitis and also notes a complication. The chart should support both the anatomic location and the presence of that complication. Check documentation if the record does not clearly identify the complication or disease extent.
Do not use for
Do not use this code for ulcerative colitis without complications, or when the record describes a different colitis type or broader disease extent. Do not assume the complication; it must be documented.
Coding tip
Verify both laterality/extent and the complication in the provider note before assigning K51.51.