K51.00 ICD-10-CM Code: Ulcerative (chronic) pancolitis without complications
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Diseases of the digestive system (K00-K95) / Noninfective enteritis and colitis (K50-K52)
K51.00
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceUlcerative (chronic) pancolitis without complications
Ulcerative colitis affecting the entire colon without complications such as bleeding, obstruction, or perforation.
Buddy Insight
Ulcerative pancolitis without complications indicates ulcerative colitis affecting the entire colon, the most extensive form of ulcerative colitis.
CMS-HCC V28
MappedHCC 81
RAF 0.0
CMS-HCC V24
MappedHCC 35
RAF 0.289
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 35
RAF 0.0
RXHCC
MappedHCC 67
RAF 0.0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
Official- Ulcerative (chronic) pancolitis NOS
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for K51.00 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for K51.00 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for K51.00 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for K51.00 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for K51.00 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for K51.00 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is K51.00 an HCC code?
Yes. K51.00 maps to Ulcerative Colitis under the CMS-HCC V28 risk adjustment model (and Inflammatory Bowel Disease under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. 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.
MEAT Criteria for K51.00
For K51.00to 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 K51.00 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
K51.00 is the ICD-10-CM diagnosis code for ulcerative (chronic) pancolitis without complications. Ulcerative colitis affecting the entire colon without complications such as bleeding, obstruction, or perforation. K51.00 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, K51.00 maps to Ulcerative Colitis (HCC 81) with a community, non-dual, aged base RAF weight of 0.000. Under the older CMS-HCC V24 model, K51.00 maps to Inflammatory Bowel Disease (HCC 35) with a community, non-dual, aged base RAF weight of 0.289. 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.
Distinguish between ulcerative colitis and Crohn's disease, as they have different code families. Because K51.00 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 K51.00 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Distinguish between ulcerative colitis and Crohn's disease, as they have different code families
- •Verify that no complications are documented before assigning this uncomplicated code
Clinical Significance
Ulcerative pancolitis without complications indicates ulcerative colitis affecting the entire colon, the most extensive form of ulcerative colitis. Pancolitis carries the highest risk for colorectal cancer among ulcerative colitis subtypes and requires more intensive surveillance. This chronic autoimmune condition requires lifelong management and significantly impacts patient care needs.
Documentation Requirements
- ✓Provider documentation of ulcerative colitis with pancolitis (entire colon involvement)
- ✓Colonoscopic or histologic evidence confirming pan-colonic involvement
- ✓Distinction from Crohn's colitis documented
- ✓Confirmation that no current complications exist (no bleeding, obstruction, abscess, fistula)
- ✓Disease activity status (remission, mild, moderate, severe) and current treatment
- ✓Colorectal cancer surveillance plan appropriate for pancolitis
Commonly Confused Codes
- •K50.10: Crohn's disease of large intestine without complications: Crohn's disease, not ulcerative colitis
- •K51.20: Ulcerative (chronic) proctitis without complications: rectum only, much more limited extent
- •K51.30: Ulcerative (chronic) rectosigmoiditis without complications: rectum and sigmoid only
- •K51.50: Left sided colitis without complications: left colon only, not pancolitis
- •K51.80: Other ulcerative colitis without complications: other specified extent
- •K51.90: Ulcerative colitis, unspecified, without complications: extent not documented