RESUMEN
In newborn babies with congenital renal pathology type agenesia, dysplasia or obstruction is very important to know if there is intrautero vicariant growing of the contralateral kidney. To find out that we have proceeded to be ultrasound volume measurement of the normal renal unit, as this is a valuable parameter related to compensatory mechanisms. We have studied by ultrasounds 28 renal units (16 right, 12 left) in newborns with contralateral pathology: pyeloureteral stenosis in 10 cases, multicystic kidney in 13 cases, renal agenesia in 3 cases, obstructive ureterocele in 1 case and another one with ureterovesical stenosis. We considered renal function, length of the larger renal axis width and depth of the kidney mass. Renal function was normal in all cases. Analysis of objectives results show a clear difference between the volume of normal Kidneys in children with contralateral pathology and the control group constituted by 42 renal unit in normal newborns without urological pathology. We conclude with the real evidence of compensatory growing of the normal contralateral kidney during intrautero periods.