K51.9 Ulcerative colitis, unspecified

Not billable (header)Chapter 11

Report one of the more specific codes below.

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Codes under this one

K51.90 Ulcerative colitis, unspecified, without complications
K51.91 Ulcerative colitis, unspecified, with complicationsHeader

Instructional notes

Chapter 11

Excludes2Not included here: the patient may have both; report both when both are present.

certain conditions originating in the perinatal period (P04-P96)
certain infectious and parasitic diseases (A00-B99)
complications of pregnancy, childbirth and the puerperium (O00-O9A)
congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
endocrine, nutritional and metabolic diseases (E00-E88)
injury, poisoning and certain other consequences of external causes (S00-T88)
neoplasms (C00-D49)
symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Section K50-K52

Excludes1Not coded here: never report with this code, except when the two conditions are unrelated.

irritable bowel syndrome (K58.-)
megacolon (K59.3-)

Includes

noninfective inflammatory bowel disease

K51

Excludes1Not coded here: never report with this code, except when the two conditions are unrelated.

Crohn's disease [regional enteritis] (K50.-)

Use additional codeAdd a second code for the full picture.

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)

Chapter 11: Diseases of the digestive system · K50-K52 Noninfective enteritis and colitis (K50-K52)

Source: ICD-10-CM FY 2027 code descriptions and tabular list (CMS and CDC National Center for Health Statistics), effective 2026-10-01 through 2027-09-30 · CMS ICD-10 files. HCC mapping: CMS-HCC V28, payment year 2027. As of 2026-11-04.

Coverage and payment depend on the claim details; confirm with the Medicare Administrative Contractor.