C18.3
BillableMalignant neoplasm of hepatic flexure
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C18.3 an HCC code?
Yes. C18.3 maps to Colorectal, Bladder, 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 C18.3
For C18.3 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 C18.3 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C18.3 is the ICD-10-CM diagnosis code for malignant neoplasm of hepatic flexure. Cancer that develops at the hepatic flexure, which is the bend in the colon where the ascending colon turns to become the transverse colon, located near the liver. C18.3 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of digestive organs (c15-c26).
Under the CMS-HCC V28 risk adjustment model, C18.3 maps to Colorectal, Bladder, and Other Cancers (HCC 22) with a community, non-dual, aged base RAF weight of 0.000. Under the older V24 model, C18.3 mapped to the same category but with a base RAF weight of 0.306 — V28 recalibrated weights across the entire model. 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.
Hepatic flexure tumors are anatomically challenging for surgical resection; document surgical approach if available. Because C18.3 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 C18.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Hepatic flexure tumors are anatomically challenging for surgical resection; document surgical approach if available
- •This location is sometimes classified with right-sided colon cancers for treatment purposes
Clinical Significance
Malignant neoplasm of the hepatic flexure occurs at the bend where the ascending colon turns to become the transverse colon, located near the liver. This location presents unique surgical challenges due to proximity to the hepatic vessels, duodenum, and right kidney. Hepatic flexure cancers are classified with right-sided cancers but require distinct surgical approaches, often needing extended right hemicolectomy.
Documentation Requirements
- ✓Documentation specifying hepatic flexure as the tumor location
- ✓Histological type confirmed by pathology
- ✓Stage of disease
- ✓Relationship to adjacent structures (liver, duodenum, kidney)
- ✓Surgical approach and extent of resection
Commonly Confused Codes
- •C18.2 — Ascending colon: the ascending colon is below the hepatic flexure; confirm documentation specifies the flexure, not just the ascending segment
- •C18.4 — Transverse colon: the transverse colon begins after the hepatic flexure; ensure the tumor is at the turn, not in the straight transverse portion
- •C78.7 — Secondary malignant neoplasm of liver: do not confuse liver metastasis with hepatic flexure primary cancer