Ulcerative colitis (K51) ICD-10-CM
The K51 code range covers ulcerative colitis with 64 ICD-10-CM diagnosis codes. 49 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Use Additional Code
The “use additional code” indicates that a secondary code could be used to further specify the patient’s condition. This note is not mandatory and is only used if enough information is available to assign an additional code.
- code to identify any associated fistulas, if applicable:
- anal fistula K60.3
- anorectal fistula K60.5
- rectal fistula K60.4
- code to identify manifestations, such as:
- pyoderma gangrenosum L88
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
- Crohn's disease [regional enteritis] K50
Codes in the K51 Range 64 codes · 49 billable
- K51 Ulcerative colitisNon-billable
- K51.0 Ulcerative (chronic) pancolitisNon-billable
- K51.00 Ulcerative (chronic) pancolitis without complications
- K51.01 Ulcerative (chronic) pancolitis with complicationsNon-billable
- K51.011 Ulcerative (chronic) pancolitis with rectal bleeding
- K51.012 Ulcerative (chronic) pancolitis with intestinal obstruction
- K51.013 Ulcerative (chronic) pancolitis with fistula
- K51.014 Ulcerative (chronic) pancolitis with abscess
- K51.018 Ulcerative (chronic) pancolitis with other complication
- K51.019 Ulcerative (chronic) pancolitis with unspecified complications
- K51.2 Ulcerative (chronic) proctitisNon-billable
- K51.20 Ulcerative (chronic) proctitis without complications
- K51.21 Ulcerative (chronic) proctitis with complicationsNon-billable
- K51.211 Ulcerative (chronic) proctitis with rectal bleeding
- K51.212 Ulcerative (chronic) proctitis with intestinal obstruction
- K51.213 Ulcerative (chronic) proctitis with fistula
- K51.214 Ulcerative (chronic) proctitis with abscess
- K51.218 Ulcerative (chronic) proctitis with other complication
- K51.219 Ulcerative (chronic) proctitis with unspecified complications
- K51.3 Ulcerative (chronic) rectosigmoiditisNon-billable
- K51.30 Ulcerative (chronic) rectosigmoiditis without complications
- K51.31 Ulcerative (chronic) rectosigmoiditis with complicationsNon-billable
- K51.311 Ulcerative (chronic) rectosigmoiditis with rectal bleeding
- K51.312 Ulcerative (chronic) rectosigmoiditis with intestinal obstruction
- K51.313 Ulcerative (chronic) rectosigmoiditis with fistula
- K51.314 Ulcerative (chronic) rectosigmoiditis with abscess
- K51.318 Ulcerative (chronic) rectosigmoiditis with other complication
- K51.319 Ulcerative (chronic) rectosigmoiditis with unspecified complications
- K51.4 Inflammatory polyps of colonNon-billable
- K51.40 Inflammatory polyps of colon without complications
- K51.41 Inflammatory polyps of colon with complicationsNon-billable
- K51.411 Inflammatory polyps of colon with rectal bleeding
- K51.412 Inflammatory polyps of colon with intestinal obstruction
- K51.413 Inflammatory polyps of colon with fistula
- K51.414 Inflammatory polyps of colon with abscess
- K51.418 Inflammatory polyps of colon with other complication
- K51.419 Inflammatory polyps of colon with unspecified complications
- K51.5 Left sided colitisNon-billable
- K51.50 Left sided colitis without complications
- K51.51 Left sided colitis with complicationsNon-billable
- K51.511 Left sided colitis with rectal bleeding
- K51.512 Left sided colitis with intestinal obstruction
- K51.513 Left sided colitis with fistula
- K51.514 Left sided colitis with abscess
- K51.518 Left sided colitis with other complication
- K51.519 Left sided colitis with unspecified complications
- K51.8 Other ulcerative colitisNon-billable
- K51.80 Other ulcerative colitis without complications
- K51.81 Other ulcerative colitis with complicationsNon-billable
- K51.811 Other ulcerative colitis with rectal bleeding
- K51.812 Other ulcerative colitis with intestinal obstruction
- K51.813 Other ulcerative colitis with fistula
- K51.814 Other ulcerative colitis with abscess
- K51.818 Other ulcerative colitis with other complication
- K51.819 Other ulcerative colitis with unspecified complications
- K51.9 Ulcerative colitis, unspecifiedNon-billable
- K51.90 Ulcerative colitis, unspecified, without complications
- K51.91 Ulcerative colitis, unspecified, with complicationsNon-billable
- K51.911 Ulcerative colitis, unspecified with rectal bleeding
- K51.912 Ulcerative colitis, unspecified with intestinal obstruction
- K51.913 Ulcerative colitis, unspecified with fistula
- K51.914 Ulcerative colitis, unspecified with abscess
- K51.918 Ulcerative colitis, unspecified with other complication
- K51.919 Ulcerative colitis, unspecified with unspecified complications
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the K51 range.
Proctocolitis
Inflammation of the RECTUM and the distal portion of the COLON.
About the K51 Code Range
The ICD-10 code K51 section categorizes ulcerative colitis and its various forms and complications, enabling precise medical diagnosis and billing. These codes specify inflammation locations, such as pancolitis, proctitis, rectosigmoiditis, and left-sided colitis, and indicate whether complications like bleeding, obstruction, fistulas, or abscesses are present.
This section includes codes like K51.00 for ulcerative (chronic) pancolitis without complications, and K51.01 for the same condition when complications such as rectal bleeding (rectal hemorrhage), intestinal obstruction, fistulas, or abscesses occur. Synonyms like "acute ulcerative colitis," "chronic ulcerative enterocolitis," and "ulcerative ileocolitis" guide coders in matching clinical terms to codes accurately. Other variants include K51.20 for ulcerative proctitis, K51.30 for rectosigmoiditis, and K51.5 for left-sided colitis, all with subcodes delineating complications. This detailed coding framework assists healthcare professionals in specifying the exact type and severity of ulcerative colitis, improving patient care documentation and treatment tracking through the ICD-10 code for ulcerative colitis.
Questions About This Page
How many billable codes are in the K51 range?
Of the 64 codes in this range, 49 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the K51 range classify?
The range classifies ulcerative colitis. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
