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 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.