Accessory kidney

This code signifies the presence of an additional, supernumerary kidney, which is a rare congenital anomaly. This extra kidney may be fully formed with its own collecting system and blood supply, or it may be rudimentary. It is distinct from a duplicated collecting system within a single kidney.

Apply this code when documentation clearly indicates the presence of an accessory kidney, often identified incidentally during imaging studies for other conditions or during workup for urinary tract anomalies. Supporting documentation includes radiology reports (e.g., ultrasound, CT, MRI) or operative reports confirming the finding.

• Ensure documentation differentiates an accessory kidney from a duplicated renal collecting system, which is coded differently.
• Code any associated symptoms or complications (e.g., hydronephrosis, infection) in addition to this code.
• This code is for a congenital anomaly; do not use for acquired renal conditions.