K51 ICD-10-CM Code: Ulcerative colitis
K51 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · HCC coding software
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FY 2026 Apr update / Diseases of the digestive system (K00-K95) / Noninfective enteritis and colitis (K50-K52)
K51
Header CodeICD-10-CMOfficial ICD-10-CMCodebook guidanceUlcerative colitis
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for K51. Check the code and parent instructions in the Code Book.
Excludes 2
Official- certain conditions originating in the perinatal period (P04-P96)Inherited from K00-K95
- certain infectious and parasitic diseases (A00-B99)Inherited from K00-K95
- complications of pregnancy, childbirth and the puerperium (O00-O9A)Inherited from K00-K95
- congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)Inherited from K00-K95
- endocrine, nutritional and metabolic diseases (E00-E88)Inherited from K00-K95
- injury, poisoning and certain other consequences of external causes (S00-T88)Inherited from K00-K95
- neoplasms (C00-D49)Inherited from K00-K95
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)Inherited from K00-K95
Related Codes
Includes
Official- noninfective inflammatory bowel diseaseInherited from K50-K52
Excludes 1
Official- Crohn's disease [regional enteritis] (K50.-)
- irritable bowel syndrome (K58.-)Inherited from K50-K52
- megacolon (K59.3-)Inherited from K50-K52
Code First
OfficialNo Code First sequencing instructions are included in this display for K51. Check the code and parent instructions in the Code Book.
Use Additional
Official- 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)
Code Also
OfficialNo Code Also instructions are included in this display for K51. Check the code and parent instructions in the Code Book.
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
- Code
- K51
- Description
- Ulcerative colitis
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF reference coefficient
- —
- Billable
- No
- Payment year
- 2026
Coder workflow notes
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What This Code Means
K51 is the ICD-10-CM diagnosis code for ulcerative colitis. K51 sits in the ICD-10-CM chapter for diseases of the digestive system (k00-k95), within the section covering noninfective enteritis and colitis (k50-k52).
Header codes like K51 cannot be reported on claims directly; they organize child codes that share clinical context. Coders should select the billable child code that matches the documented presentation and then verify its current source-backed HCC mapping. Do not infer a child code or risk adjustment value from the header alone.
HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for K51 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Excludes 1, Do NOT code together
- Crohn's disease [regional enteritis] (K50.-)