Duplex systems.

Duplex kidneys occur in 0.8% of the general population, many of whom are asymptomatic. Children with duplex kidneys may be prone to urinary tract infections because of vesico-ureteric reflux or obstruction. Surgical management is usually required once symptoms occur. Increasing numbers of duplex kidneys are now prenatally diagnosed by ultrasound, resulting in the development of early postnatal strategies to try and reduce morbidity.