ICD-10 Code K51.3 – Ulcerative (chronic) rectosigmoiditis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K51.3 – Ulcerative (chronic) rectosigmoiditis
What it is
K51.3 identifies chronic ulcerative colitis limited to the rectum and sigmoid colon. Use it when documentation specifies rectosigmoid involvement rather than more extensive disease.
Clinical signs
Typical findings include chronic bloody diarrhea, urgency, rectal bleeding, and lower abdominal cramping. Clinical features vary; refer to documentation, especially when the record distinguishes limited distal colitis from broader ulcerative colitis.
When to use this code
Use K51.3 when the provider documents ulcerative colitis affecting the rectum and sigmoid colon, or uses terms such as rectosigmoiditis with a chronic ulcerative pattern. It also fits follow-up visits for established disease when the anatomic location remains the same. If the extent is unclear, check documentation before coding.
Do not use for
Do not use this code for ulcerative colitis involving only the rectum, more extensive colitis, or non-ulcerative inflammatory bowel disease. Check documentation if the site is described differently or not specified.
Coding tip
Code the documented anatomic extent exactly; rectosigmoid disease is not the same as proctitis or pancolitis.