[Diagnosis in neonatal hydronephrosis]

Maternal ultrasonography makes it possible to detect hydronephrosis in the fetus. After birth, hydronephrosis should be confirmed by repeating the ultrasonic examination. Reflux may coexist with all causes of hydronephrosis, for which reason it is necessary to do a voiding cystourethrogram. It is also necessary to do a renography, partly to estimate the relative renal function of each kidney, and partly to estimate the drainage function. In most cases ultrasound, voiding cystourethrography and renography are able to reveal the cause of hydronephrosis. Only in case of doubt it is necessary to do an excretory urography, which is rendered difficult by excessive bowel gas and poor renal function in neonates.