K51.919 maps to CMS-HCC V28 81. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · free HCC coding tools

ICD-10-CM Code View

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Code lookupK51.919

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

K51.919

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

Ulcerative colitis, unspecified with unspecified complications

Ulcerative colitis of unspecified extent with a complication that is not specified or identified.

Buddy Insight

Ulcerative colitis, unspecified, with unspecified complications is the least specific code in the ulcerative colitis category, lacking both anatomic extent and complication type.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 81

Ulcerative Colitis

Coefficient HCC 81: 0.244 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 048

HHS-HCC 048 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 35

Inflammatory Bowel Disease

Code-level coefficient reference

RXHCC

Mapped

HCC 67

Inflammatory Bowel Disease

Code-level coefficient reference

Code Book Path

Official

K51.9Ulcerative colitis, unspecified K51.91Ulcerative colitis, unspecified, with complications K51.919Ulcerative colitis, unspecified with unspecified complications

Inclusion Terms

Official

No inclusion terms are included in this display for K51.919. 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

Official

K51.911Ulcerative colitis, unspecified with rectal bleeding 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

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

Official

No Code First sequencing instructions are included in this display for K51.919. 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

Official

No Code Also instructions are included in this display for K51.919. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Confirmed ulcerative colitis diagnosis

Provider acknowledgment that complications exist

Documentation of dual provider queries: one for disease extent and one for complication type

Treatment plan addressing the colitis and complications

MEAT Support

HCC Buddy guidance

Confirmed ulcerative colitis diagnosis

Provider acknowledgment that complications exist

Documentation of dual provider queries: one for disease extent and one for complication type

Treatment plan addressing the colitis and complications

Audit Caution

HCC Buddy guidance

Using this maximally unspecified code without exhausting all avenues for clarification

Not querying the provider for both the disease extent and the complication type

Defaulting to this code out of convenience rather than thorough chart review

Not leveraging colonoscopy reports, imaging studies, and surgical notes that may provide specificity

Common Mistakes

HCC Buddy guidance

K51.919 vs K51.918 — K51.918 is when the complication is identified but non-standard

K51.919 vs K51.90 — K51.90 is without complications; different clinical situation

K51.919 vs any extent-specific code with specific complication — Always prefer the most specific code available

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 K51.919 an HCC code?

Yes. K51.919 (Ulcerative colitis, unspecified with unspecified complications) maps to HCC 81, Ulcerative Colitis under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.244. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: K51.919 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: K51.919
Description: Ulcerative colitis, unspecified with unspecified complications
HCC (V28): HCC 81 — Ulcerative Colitis
RAF reference coefficient: 0.244
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 81, Ulcerative Colitis

0.244

ESRDHCC 35, Inflammatory Bowel Disease

Not separately weighted

RxHCCHCC 67, Inflammatory Bowel Disease

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. 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 context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work K51.919 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for K51.919

For K51.919, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

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

Coder workflow notes

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What This Code Means

K51.919 is the ICD-10-CM diagnosis code for ulcerative colitis, unspecified with unspecified complications. Ulcerative colitis of unspecified extent with a complication that is not specified or identified. K51.919 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, K51.919 maps to Ulcerative Colitis (HCC 81) with a source-labeled community, non-dual, aged reference coefficient of 0.244. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

This is a last-resort code; always query the provider to identify the specific complication for more accurate coding. For K51.919, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, and MEAT documentation criteria for K51.919 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This is a last-resort code; always query the provider to identify the specific complication for more accurate coding.
•Avoid using this code if the complication can be determined from clinical documentation.

Clinical Significance

Ulcerative colitis, unspecified, with unspecified complications is the least specific code in the ulcerative colitis category, lacking both anatomic extent and complication type. This code should be a last resort and always triggers provider queries for both the disease extent and the nature of complications, as more precise coding is almost always achievable.

Documentation Requirements

✓Confirmed ulcerative colitis diagnosis
✓Provider acknowledgment that complications exist
✓Documentation of dual provider queries: one for disease extent and one for complication type
✓Treatment plan addressing the colitis and complications
✓Plan for colonoscopy to determine disease extent if not already performed

Commonly Confused Codes

•K51.919 vs K51.918: K51.918 is when the complication is identified but non-standard
•K51.919 vs K51.90: K51.90 is without complications; different clinical situation
•K51.919 vs any extent-specific code with specific complication: Always prefer the most specific code available