K51 – Ulcerative colitis

ICD-10-CM 2027 diagnosis code · Noninfective enteritis and colitis

Non-billable header

ICD-10-CM code K51

Code: K51 (claims format: K51)
Description: Ulcerative colitis
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 11. Diseases of the digestive system (K00-K95)
Block: K50-K52 Noninfective enteritis and colitis

Billable codes under K51

K51 is a header code and cannot be used on claims. Choose the most specific code:

K51.0 – Ulcerative (chronic) pancolitisHeader (more codes below)
K51.2 – Ulcerative (chronic) proctitisHeader (more codes below)
K51.3 – Ulcerative (chronic) rectosigmoiditisHeader (more codes below)
K51.4 – Inflammatory polyps of colonHeader (more codes below)
K51.5 – Left sided colitisHeader (more codes below)
K51.8 – Other ulcerative colitisHeader (more codes below)
K51.9 – Ulcerative colitis, unspecifiedHeader (more codes below)

Notes for K51

Excludes1 (not coded here):

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

Use 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)

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

Block K50-K52

Includes:

noninfective inflammatory bowel disease

Excludes1 (not coded here):

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

Frequently asked questions

What is ICD-10 code K51?

K51 is the ICD-10-CM code for ulcerative colitis, in the block K50-K52 (Noninfective enteritis and colitis).

Is K51 a billable code?

No. K51 is a header code with more specific child codes; report one of the billable codes listed above.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.