K55.9
BillableVascular disorder of intestine, unspecified
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is K55.9 an HCC code?
Yes. K55.9 maps to Vascular Disease under the V24 model but is not retained in V28.
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 K55.9
For K55.9to 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 K55.9 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
K55.9 is the ICD-10-CM diagnosis code for vascular disorder of intestine, unspecified. A blood vessel disorder of the intestines where the specific type or nature is not clearly documented or identified. K55.9 sits in the ICD-10-CM chapter for diseases of the digestive system (k00-k95), within the section covering other diseases of intestines (k55-k64).
Under the older CMS-HCC V24 model, K55.9 maps to Vascular Disease (HCC 108) with a community, non-dual, aged base RAF weight of 0.297. 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.
This is a non-specific code; query the provider for more detail to assign a more specific K55 code. Because K55.9 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 K55.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a non-specific code; query the provider for more detail to assign a more specific K55 code
- •Use only when insufficient information is available to determine the exact type of vascular disorder
Clinical Significance
K55.9 represents an unspecified vascular disorder of the intestine, indicating blood supply compromise without clear specification of the exact type. This diagnosis suggests intestinal vascular pathology requiring further evaluation and monitoring for potential complications including bowel ischemia and perforation.
Documentation Requirements
- ✓Clinical presentation suggesting intestinal vascular compromise
- ✓Documentation that specific type of vascular disorder cannot be determined
- ✓Evidence of diagnostic workup attempting to classify the vascular disorder
- ✓Exclusion of other specific vascular conditions through documentation
- ✓Symptoms consistent with compromised intestinal blood supply
- ✓Imaging or laboratory findings supporting vascular etiology
- ✓Treatment plan addressing suspected vascular component
- ✓Follow-up plan for further diagnostic clarification
Commonly Confused Codes
- •K55.8 — Other vascular disorders (used when specific type is known but not otherwise classified)
- •K55.0 — Acute vascular disorders (more specific acute condition)
- •K55.1 — Chronic vascular disorders (more specific chronic condition)
- •K92.2 — Gastrointestinal hemorrhage unspecified (bleeding rather than vascular disorder)
- •K59.9 — Functional intestinal disorder unspecified (functional rather than vascular)