Supernumerary kidney

Last revised by Dr Fabio Macori on 27 Feb 2022

Supernumerary kidneys, also known as accessory kidneys, are a rare congenital anomaly of the urogenital system, where there are one or two additional kidneys.

Less than 100 cases have been documented in the medical literature.

Many conditions have been found to be associated with supernumerary kidneys including:

Patients may be asymptomatic. If present, symptoms may encompass fever, pain and an abdominal mass. These symptoms are mostly due to related renal pathologies such as hydronephrosis, pyelonephritis, malignant tumors or calculi.

Most of the supernumerary kidneys are on the left and usually caudal to the native kidney. Mostly the accessory kidney is smaller in size with reduced excretion. The evaluation may be done by ultrasound, IVU, CT, MRI and nuclear medicine studies like DMSA and DTPA scans. Ultrasound is useful in morphological characterization whilst the rest may aid in the functional assessment too.

Management is symptom-based.  For asymptomatic patients, regular ultrasound follow-ups and USG with excretory function assessment is suggested if the patient is symptomatic. 

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Cases and figures

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