Congenital anomalies of the kidneys and urinary tract include a wide range of defects that have their origin during the critical period of organogenesis of urinary system. The conditions includes a full spectrum and array of defects and can include minor conditions, such as mild resolving hydronephrosis, all the way to anuric renal failure due to posterior urethral valves or bilateral renal agenesis. Its etiologies can include many of genes known to be critical in urinary tract development, as well as environtmental factors that can interfere with development at key stages, however, in the majority of cases, the etiology remains unknown. Most cases can be detected and diagnosed prenatally with modern antenatal ultrasonography.
Lower urinary tract obstruction secondary to posterior urethral valves shows a biphasic peak incidence for time to progression to end-stage renal disease, with the first peak being in infancy and the second peak occuring in adolescents. In the most severe cases, the kidneys are so dysplastic and poorly developed that there is severe oliguric kidney failure at the time of birth or very soon afterwards. Many of the seemingly less severe cases still result in highly dysplastic kidneys, which display poor growth over time, eventually culminating in end-stage renal disease.
Infant dialysis is technically challenging and costly, therefore, it would be helpful to have a clear idea of which patients would be at highest risk for early renal failure. Dialysis can be problematic in the newborn and requires strong nephrologic expertise, which may not available at all institution. However, over the last 20 years, renal replacement therapy has improved outcomes in infants and children, and success has been reported.
For children with end-stage renal disease, dialysis is generally considered a bridging step until kidney transplantation is possible. Assesing the odds for successful kidney transplantation, 10 kg is generally agreed to be the smallest size. To support a newborn with end-stage renal disease to the 10 kg mark, intensive nutritional therapy, often with tube feeding, is required. These infants generally have oral aversions and have failure to thrive due to frequent vomiting and an increased catabolism.