[Prenatal ultrasound diagnosis in congenital abnormalities of the kidneys and efferent urinary tract from the pediatric nephrology viewpoint].

Antenatal foetal abnormalities are found in 0.5% of all pregnancies. 30-50% of these abnormalities are related to the urinary tract. Although congenital abnormalities of the urinary tract can be detected as early as in the 15th-18th weeks of gestation, most abnormalities are detected between the 28th-30th weeks of gestation. At this time irreversible damage of the kidneys has taken place and the foetus will not benefit from antenatal therapy. On the other hand, a foetus with late onset of obstruction will benefit from antenatal intervention. Repeated ultrasonography is crucial for initiating further invasive diagnostic procedures, antenatal therapy and for planning the time of labour. There is a great risk of overdiagnosis and inadequate therapy because 25% of all antenatally diagnosed dilatations of the urinary tract could not be confirmed postnatally.