What is ICD-10 code K51.911?

K51.911 is the ICD-10-CM diagnosis code for Ulcerative colitis, unspecified with rectal bleeding. Ulcerative colitis of unspecified extent with bleeding from the rectum. It belongs to the ICD-10-CM chapter for diseases of the digestive system (k00-k95). K51.911 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. K51.911 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. K51.911 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. K51.911 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does K51.911 map to under V28?

K51.911 maps to CMS-HCC V28 81 (Ulcerative Colitis). The category number and label come from the CMS-HCC V28 model file for payment year 2026.

What does K51.911 pay in RAF?

K51.911 carries a community, non-dual, aged (CNA) RAF weight of 0.244 under CMS-HCC V28 for payment year 2026. The weight comes from the CMS V28 relative-factor file, not a hand-typed table.

What is the V28 vs V24 difference for K51.911?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For K51.911, V28 maps to Ulcerative Colitis at RAF 0.244 while V24 mapped to Inflammatory Bowel Disease at RAF 0.308. Both models can still appear in legacy data and in payer-specific lookback periods.

What documentation supports K51.911?

Document the severity of bleeding (minor vs. significant) as this may impact clinical management and coding specificity. Ensure rectal bleeding is directly attributed to the ulcerative colitis and not from another source. Because K51.911 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score. See the MEAT criteria checklist at /meat-criteria for what Monitor, Evaluate, Assess, or Treat looks like in a note. MEAT is generic documentation evidence, not a payer-specific rule.

2026 ICD-10-CM K51.911: Ulcerative colitis

K51.911 maps to CMS-HCC V28 81 (RAF 0.244). Documentation must support MEAT. MEAT criteria · RAF calculator · HCC Buddy coding tools

ICD-10-CM Code View

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Code lookupK51.911Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the digestive system (K00-K95) / Noninfective enteritis and colitis (K50-K52)

K51.911

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Ulcerative colitis, unspecified with rectal bleeding

Ulcerative colitis of unspecified extent with bleeding from the rectum.

Buddy Insight

Ulcerative colitis, unspecified, with rectal bleeding indicates active hemorrhagic disease but without documentation of the anatomic extent.

CMS-HCC V28

Mapped

HCC 81

Ulcerative Colitis

RAF 0.244

CMS-HCC V24

Mapped

HCC 35

Inflammatory Bowel Disease

RAF 0.308

ACA/HHS

Mapped

HCC 48

HHS-HCC 48

Varies by metal level

ESRD/PACE

Mapped

HCC 35

Inflammatory Bowel Disease

RAF 0.048

RXHCC

Mapped

HCC 67

Inflammatory Bowel Disease

RAF 0.494

Code Book Path

Official

K51.9Ulcerative colitis, unspecified

K51.91Ulcerative colitis, unspecified, with complications

K51.911Ulcerative colitis, unspecified with rectal bleeding

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for K51.911 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for K51.911 in this effective period.

Related Child Codes

Official

K51.912Ulcerative colitis, unspecified with intestinal obstruction

K51.913Ulcerative colitis, unspecified with fistula

K51.914Ulcerative colitis, unspecified with abscess

K51.918Ulcerative colitis, unspecified with other complication

K51.919Ulcerative colitis, unspecified with unspecified complications

Includes

Official

ICD-10-CM does not list Includes notes for K51.911 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for K51.911 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for K51.911 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for K51.911 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for K51.911 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Confirmed ulcerative colitis diagnosis

Documentation of rectal bleeding including severity and frequency

Provider attribution of bleeding to the ulcerative colitis

Laboratory values if clinically significant bleeding

MEAT Support

HCC Buddy guidance

Confirmed ulcerative colitis diagnosis

Documentation of rectal bleeding including severity and frequency

Provider attribution of bleeding to the ulcerative colitis

Laboratory values if clinically significant bleeding

Audit Caution

HCC Buddy guidance

Using this unspecified code when the anatomic extent has been determined by colonoscopy

Coding rectal bleeding separately instead of using the combination code

Not querying for disease extent when colonoscopy data is available

Using K51.90 (without complications) when rectal bleeding is documented

Common Mistakes

HCC Buddy guidance

K51.911 vs K51.011/K51.211/K51.311/K51.511/K51.811 — Use extent-specific codes with rectal bleeding when extent is known

K51.911 vs K62.5 — K62.5 is hemorrhage of anus/rectum not related to inflammatory bowel disease

K51.911 vs K51.90 — K51.90 is without complications; use K51.911 when bleeding is present

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 →

Is K51.911 an HCC code?

Yes. K51.911 (Ulcerative colitis, unspecified with rectal bleeding) maps to Ulcerative Colitis under the CMS-HCC V28 risk adjustment model (and Inflammatory Bowel Disease under V24), with a community non-dual aged RAF of 0.244. It is billable for payment year 2026.

Coder answer: K51.911 is billable and maps to V28 HCC 81, Ulcerative Colitis. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: K51.911
Description: Ulcerative colitis, unspecified with rectal bleeding
HCC (V28): HCC 81 — Ulcerative Colitis
RAF: 0.244
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 81, Ulcerative Colitis

0.244

V24HCC 35, Inflammatory Bowel Disease

0.308

ESRDHCC 35, Inflammatory Bowel Disease

0.048

RxHCCHCC 67, Inflammatory Bowel Disease

0.494

Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

Work K51.911 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for K51.911

For K51.911 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed K51.911 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

K51.911 is the ICD-10-CM diagnosis code for ulcerative colitis, unspecified with rectal bleeding. Ulcerative colitis of unspecified extent with bleeding from the rectum. K51.911 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).

Under the CMS-HCC V28 risk adjustment model, K51.911 maps to Ulcerative Colitis (HCC 81) with a community, non-dual, aged base RAF weight of 0.244. Under the older CMS-HCC V24 model, K51.911 maps to Inflammatory Bowel Disease (HCC 35) with a community, non-dual, aged base RAF weight of 0.308. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Document the severity of bleeding (minor vs. significant) as this may impact clinical management and coding specificity. Because K51.911 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for K51.911 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Document the severity of bleeding (minor vs. significant) as this may impact clinical management and coding specificity.
•Ensure rectal bleeding is directly attributed to the ulcerative colitis and not from another source.

Clinical Significance

Ulcerative colitis, unspecified, with rectal bleeding indicates active hemorrhagic disease but without documentation of the anatomic extent. The rectal bleeding confirms active disease requiring treatment, while the unspecified extent suggests the need for colonoscopy or provider query to determine disease distribution for optimal management.

Documentation Requirements

✓Confirmed ulcerative colitis diagnosis
✓Documentation of rectal bleeding including severity and frequency
✓Provider attribution of bleeding to the ulcerative colitis
✓Laboratory values if clinically significant bleeding
✓Treatment plan for active disease and bleeding
✓Plan to determine disease extent via colonoscopy

Commonly Confused Codes

•K51.911 vs K51.011/K51.211/K51.311/K51.511/K51.811: Use extent-specific codes with rectal bleeding when extent is known
•K51.911 vs K62.5: K62.5 is hemorrhage of anus/rectum not related to inflammatory bowel disease
•K51.911 vs K51.90: K51.90 is without complications; use K51.911 when bleeding is present