ICD-10 Code C66.1 – Malignant neoplasm of right ureter (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C66.1 – Malignant neoplasm of right ureter
What it is
C66.1 identifies a malignant tumor arising in the right ureter, the tube that carries urine from the right kidney to the bladder. Use it when documentation clearly states cancer of the right ureter.
Clinical signs
Clinical features may include hematuria, flank pain, or urinary obstruction, but presentation can be subtle. Diagnosis is usually supported by imaging, endoscopic findings, or pathology; clinical features vary, refer to documentation.
When to use this code
Use C66.1 when the provider documents primary malignancy of the right ureter, including confirmed urothelial carcinoma in that location. It also fits when laterality is specified as right and no more specific site code is given.
If the record only says ureter cancer without laterality, check documentation before coding. Code the confirmed diagnosis, not suspected disease, and follow sequencing rules when other malignancies or metastases are documented.
Do not use for
Do not use this code for benign ureteral tumors, kidney cancer, or bladder cancer. Do not assign it when the chart does not specify the right ureter or when documentation is uncertain.
Coding tip
Verify laterality and primary site in the pathology or operative note before assigning C66.1.