What is ICD-10 code K51.40?

K51.40 is the ICD-10-CM diagnosis code for Inflammatory polyps of colon without complications. Growths in the colon caused by inflammation, without any additional complications. It belongs to the ICD-10-CM chapter for diseases of the digestive system (k00-k95). K51.40 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. K51.40 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. K51.40 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. K51.40 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.

What is the V28 vs V24 difference for K51.40?

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 K51.40, 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 should coders know when reporting K51.40?

Use this code only when inflammatory polyps are documented without complications; if any complication is present, use a more specific code from the K51.41x series Distinguish between inflammatory polyps (K51.4x) and other types of colonic polyps; inflammatory polyps are specifically associated with inflammatory bowel disease Because K51.40 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.

2026 ICD-10-CM K51.40: Inflammatory polyps of colon

ICD-10-CM Code View

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Code lookupK51.40Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

K51.40

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

Inflammatory polyps of colon without complications

Growths in the colon caused by inflammation, without any additional complications.

Buddy Insight

Inflammatory polyps (pseudopolyps) of the colon without complications are non-neoplastic growths that develop as a result of chronic inflammatory bowel disease.

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

K51Ulcerative colitis

K51.4Inflammatory polyps of colon

K51.40Inflammatory polyps of colon without complications

Inclusion Terms

Official

Inflammatory polyps of colon NOS

Excludes 2

Official

adenomatous polyp of colon (D12.6)
polyposis of colon (D12.6)
polyps of colon NOS (K63.5)

Related Child Codes

Official

K51.41Inflammatory polyps of colon with complications

Includes

Official

ICD-10-CM does not list Includes notes for K51.40 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for K51.40 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for K51.40 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for K51.40 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for K51.40 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Colonoscopy report documenting inflammatory (pseudo)polyps

Biopsy confirmation that polyps are inflammatory in nature, not adenomatous or dysplastic

Documentation that these are associated with underlying ulcerative colitis

Statement confirming no complications are present

MEAT Support

HCC Buddy guidance

Colonoscopy report documenting inflammatory (pseudo)polyps

Biopsy confirmation that polyps are inflammatory in nature, not adenomatous or dysplastic

Documentation that these are associated with underlying ulcerative colitis

Statement confirming no complications are present

Audit Caution

HCC Buddy guidance

Confusing inflammatory pseudopolyps with adenomatous polyps and coding with D12.x neoplasm codes

Not distinguishing between inflammatory polyps (related to ulcerative colitis) and sporadic colonic polyps (K63.5)

Failing to biopsy polyps to confirm they are inflammatory rather than dysplastic in the setting of ulcerative colitis

Using the unspecified ulcerative colitis code when inflammatory polyps are specifically documented

Common Mistakes

HCC Buddy guidance

K51.40 vs K63.5 — K63.5 is polyp of colon (non-inflammatory); K51.40 is specifically for inflammatory pseudopolyps related to ulcerative colitis

K51.40 vs D12.x — D12 codes are for benign neoplastic polyps (adenomas); inflammatory polyps are not neoplastic

K51.40 vs K51.00 — K51.00 is pancolitis without complications; K51.40 specifically captures inflammatory polyps

K51.40 vs K51.80 — K51.80 is other ulcerative colitis without complications; inflammatory polyps have their own specific subcategory

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 K51.40 an HCC code?

Yes. K51.40 (Inflammatory polyps of colon without complications) 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: K51.40 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: K51.40
Description: Inflammatory polyps of colon without complications
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 K51.40 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for K51.40

For K51.40 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 K51.40 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

K51.40 is the ICD-10-CM diagnosis code for inflammatory polyps of colon without complications. Growths in the colon caused by inflammation, without any additional complications. K51.40 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, K51.40 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, K51.40 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.

Use this code only when inflammatory polyps are documented without complications; if any complication is present, use a more specific code from the K51.41x series. Because K51.40 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 K51.40 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Use this code only when inflammatory polyps are documented without complications; if any complication is present, use a more specific code from the K51.41x series
•Distinguish between inflammatory polyps (K51.4x) and other types of colonic polyps; inflammatory polyps are specifically associated with inflammatory bowel disease

Clinical Significance

Inflammatory polyps (pseudopolyps) of the colon without complications are non-neoplastic growths that develop as a result of chronic inflammatory bowel disease. While not directly precancerous, they indicate prior severe inflammation and mucosal damage, complicate colonoscopic surveillance for dysplasia, and confirm a history of significant inflammatory bowel disease activity.

Documentation Requirements

✓Colonoscopy report documenting inflammatory (pseudo)polyps
✓Biopsy confirmation that polyps are inflammatory in nature, not adenomatous or dysplastic
✓Documentation that these are associated with underlying ulcerative colitis
✓Statement confirming no complications are present
✓Distinction from other polyp types (adenomatous, serrated, hyperplastic)
✓Surveillance plan based on inflammatory bowel disease guidelines

Commonly Confused Codes

•K51.40 vs K63.5: K63.5 is polyp of colon (non-inflammatory); K51.40 is specifically for inflammatory pseudopolyps related to ulcerative colitis
•K51.40 vs D12.x: D12 codes are for benign neoplastic polyps (adenomas); inflammatory polyps are not neoplastic
•K51.40 vs K51.00: K51.00 is pancolitis without complications; K51.40 specifically captures inflammatory polyps
•K51.40 vs K51.80: K51.80 is other ulcerative colitis without complications; inflammatory polyps have their own specific subcategory