ICD-10 Code C66 – Malignant neoplasm of ureter (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C66 – Malignant neoplasm of ureter
What it is
C66 identifies a malignant tumor arising in the ureter, the tube that carries urine from the kidney to the bladder. Use it when the record documents primary cancer of the ureter.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings include hematuria, flank pain, or imaging evidence of a ureteral mass or obstruction, but diagnosis should be supported by the provider’s assessment.
When to use this code
Use C66 when the provider documents a primary malignant neoplasm of the ureter, including laterality-specific or site-specific ureteral cancer when no more detailed code is available. It may also apply when pathology, imaging, or operative notes confirm a ureteral primary. Check documentation if the tumor could represent spread from another site.
Do not use for
Do not use C66 for benign ureteral tumors, ureteral stones, or nonspecific urinary tract symptoms. If the cancer is metastatic to the ureter or the primary site is elsewhere, code the documented primary cancer instead.
Coding tip
Confirm whether the ureter lesion is primary, metastatic, or unspecified before assigning C66.