ICD-10 Code C66.9 – Malignant neoplasm of unspecified ureter (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C66.9 – Malignant neoplasm of unspecified ureter
What it is
This code identifies a malignant tumor arising in the ureter when the site is not further specified. Use it when documentation confirms ureter cancer but does not identify right or left side.
Clinical signs
Clinical features vary; refer to documentation. Commonly reported findings may include hematuria, flank pain, or imaging evidence of a ureteral mass or obstruction, but the diagnosis must be confirmed in the record.
When to use this code
Use C66.9 when the provider documents primary ureter cancer and laterality is not stated. It is appropriate for pathology, imaging, or operative reports that identify a malignant neoplasm of the ureter without specifying which ureter. If the record later clarifies side, code the specified ureter instead.
Do not use for
Do not use this code for benign ureter lesions, metastatic disease to the ureter, or cancers documented as kidney, bladder, or renal pelvis tumors. Check documentation if the site is unclear.
Coding tip
Query the provider if the ureter side is missing, because laterality-specific codes are preferred when documented.