Duplex Kidney

What is a duplex kidney?

In a normal urinary tract, each kidney is connected to one ureter (a tube that drains urine into the bladder).

Children with a duplex kidney (also called a duplicated collecting system) have two ureters coming from a single kidney. These two ureters can drain independently into the bladder or connect and drain as a single ureter into the bladder. Duplex kidneys can occur in one or both kidneys.

Duplex Kidney Illustration

Duplex kidneys are a normal variant, meaning that they occur commonly enough in healthy children to be considered normal. They occur in 1 percent of the population, and most cause no medical problems and will require no treatment.

Other duplex kidneys can be associated with the following:

Testing and diagnosis

Many duplex kidneys are found incidentally during imaging studies.


Since most duplex kidneys are a normal finding, no treatment is necessary. If a duplicated kidney is associated with VUR, an ectopic ureter or a ureterocele, experts in the Division of Urology will follow the treatment plan for those diagnoses.

Reviewed by: Division of Urology
Date: May 2011

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