C66.2
BillableMalignant neoplasm of left ureter
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C66.2 an HCC code?
Yes. C66.2 maps to Bladder, Colorectal, and Other Cancers under the CMS-HCC V28 risk adjustment model (and Colorectal, Bladder, and Other Cancers 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 C66.2
For C66.2to 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 C66.2 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C66.2 is the ICD-10-CM diagnosis code for malignant neoplasm of left ureter. Cancer that starts in the left tube (ureter) that carries urine from the kidney to the bladder. C66.2 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of urinary tract (c64-c68).
Under the CMS-HCC V28 risk adjustment model, C66.2 maps to Bladder, Colorectal, and Other Cancers (HCC 22) with a community, non-dual, aged base RAF weight of 0.363. Under the older CMS-HCC V24 model, C66.2 maps to Colorectal, Bladder, and Other Cancers (HCC 11) with a community, non-dual, aged base RAF weight of 0.307. 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.
Verify laterality is documented as left; if not specified, use C66.9 instead. Because C66.2 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 C66.2 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify laterality is documented as left; if not specified, use C66.9 instead
- •Confirm histological type and stage are documented for complete coding
Clinical Significance
Left ureteral cancer is an upper tract urothelial carcinoma with the same clinical implications as right-sided disease. Laterality is critical for surgical planning and for determining the impact on overall renal function, particularly if the contralateral kidney has any impairment. Long-term bladder surveillance is mandatory due to the high risk of subsequent bladder cancer.
Documentation Requirements
- ✓Pathology confirming left ureteral malignancy
- ✓Histologic type and grade
- ✓Location within the ureter
- ✓Staging information
- ✓Treatment plan
- ✓Contralateral kidney and ureter status
Commonly Confused Codes
- •C65.2 — Left renal pelvis cancer; different location within the upper tract
- •C66.1 — Right ureter cancer; verify laterality
- •C66.9 — Unspecified ureter; use C66.2 when left is documented
- •C67.6 — Ureteric orifice of bladder; the distal ureter and ureteric orifice are at the junction but coded differently