K51.9 ICD-10-CM Code: Ulcerative colitis, unspecified
K51.9 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)
K51.9
Header CodeICD-10-CMOfficial ICD-10-CMCodebook guidanceUlcerative colitis, unspecified
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 K51.9. 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- irritable bowel syndrome (K58.-)Inherited from K50-K52, K51
- megacolon (K59.3-)Inherited from K50-K52, K51
- Crohn's disease [regional enteritis] (K50.-)Inherited from K50-K52, K51
Code First
OfficialNo Code First sequencing instructions are included in this display for K51.9. Check the code and parent instructions in the Code Book.
Use Additional
Official- code to identify any associated fistulas, if applicable:Inherited from K51
- anal fistula (K60.3-)Inherited from K51
- anorectal fistula (K60.5-)Inherited from K51
- rectal fistula (K60.4-)Inherited from K51
- code to identify manifestations, such as:Inherited from K51
- pyoderma gangrenosum (L88)Inherited from K51
Code Also
OfficialNo Code Also instructions are included in this display for K51.9. 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
- K51.9
- Description
- Ulcerative colitis, unspecified
- 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
K51.9 is the ICD-10-CM diagnosis code for ulcerative colitis, unspecified. K51.9 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 K51.9 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 K51.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.