2026 ICD-10-CM Diagnosis Code K51Ulcerative colitis

ICD-10-CM Codes›K00–K95›K50-K52›K51

ICD-10-CM K51
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K51 is a non-billable ICD-10-CM category code for ulcerative colitis, so it cannot be submitted on claims. Use a more specific code from this category instead, such as K51.00, K51.011, K51.012, and K51.013.

Code Identity

ICD-10-CM Code
K51
Billable Status
No — Non-Billable Category
Code Describes
Ulcerative colitis
Chapter
K50-K52
Noninfective enteritis and colitis

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK50-K52Noninfective enteritis and colitis
CategoryK51Ulcerative colitis
This CodeK51Ulcerative colitis

Specific Coding for Ulcerative colitisOverview

Non-specific codes like K51 require more characters. Use one of these billable codes instead:

  • K51.0 for Ulcerative (chronic) pancolitis

  • Use K51.00 for Ulcerative (chronic) pancolitis without complications

  • K51.01 for Ulcerative (chronic) pancolitis with complications

  • K51.2 for Ulcerative (chronic) proctitis

  • Use K51.20 for Ulcerative (chronic) proctitis without complications

  • K51.21 for Ulcerative (chronic) proctitis with complications

  • K51.3 for Ulcerative (chronic) rectosigmoiditis

  • Use K51.30 for Ulcerative (chronic) rectosigmoiditis without complications

  • K51.31 for Ulcerative (chronic) rectosigmoiditis with complications

  • K51.4 for Inflammatory polyps of colon

  • Use K51.40 for Inflammatory polyps of colon without complications

  • K51.41 for Inflammatory polyps of colon with complications

  • K51.5 for Left sided colitis

  • Use K51.50 for Left sided colitis without complications

  • K51.51 for Left sided colitis with complications

  • K51.8 for Other ulcerative colitis

  • Use K51.80 for Other ulcerative colitis without complications

  • K51.81 for Other ulcerative colitis with complications

  • K51.9 for Ulcerative colitis, unspecified

  • Use K51.90 for Ulcerative colitis, unspecified, without complications

  • K51.91 for Ulcerative colitis, unspecified, with complications

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Use Additional Code

  • code to identify any associated fistulas, if applicable:
  • anal fistula K60.3
  • anorectal fistula K60.5
  • rectal fistula K60.4

Type 1 Excludes

  • Crohn's disease regional enteritis K50

Patient EducationClinical

Ulcerative Colitis

Ulcerative colitis (UC) is a disease that causes inflammation and sores, called ulcers, in the lining of the rectum and colon. It is one of a group of diseases called inflammatory bowel disease.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About K51Overview

Is K51 (Ulcerative colitis) a billable code?

No. This is a category header that groups the codes for ulcerative colitis, and headers cannot be submitted on claims. Claims for ulcerative colitis need a more specific code from this category, such as K51.00, K51.011, and K51.012.