DIAGNOSTIC-CRITERIA FOR ASSESSING OBSTRUCTION IN THE NEWBORN WITH UNILATERAL HYDRONEPHROSIS USING THE RENAL GROWTH RENAL-FUNCTION CHART

Previous studies in newborns with unilateral hydronephrosis demonstrat ed that the contralateral normal kidney can rapidly compensate for cha nges in function in the hydronephrotic kidney by increasing or decreas ing its growth rate. To formulate diagnostic criteria for assessing ob struction using compensatory growth responses we developed a renal gro wth-renal function chart that graphically describes the normal renal g rowth rate in young children. This chart allows changes in function in the hydronephrotic kidney to be graphically compared to changes in le ngth of the contralateral normal kidney. The renal growth-renal functi on chart was used to assess obstruction in 47 neonates with primary un ilateral hydronephrosis. Four reproducible, clinically relevant diagno stic patterns of differential function and growth were identified: 1) obstruction, 2) corrected obstruction, 3) no obstruction with good dif ferential function (greater than 40%) and 4) no obstruction but poor d ifferential function (less than 40%). The renal growth-renal function chart helped to identify and exclude obstruction, and provided welcome reassurance that nonobstructive hydronephrosis was not harming the ki dney. It appears to have potential for improving diagnostic accuracy i n newborns with hydronephrosis.