[Diagnostic approach to newborns with prenatal diagnosis of hydronephrosis]

Prenatal ultrasound examination has radically changed physician's attitude toward hydronephrosis. Fetal hydronephrosis must be searched out and looked at with a wider vision than it was done in the past. A mechanical obstruction must be suspected indeed, but often we have to face a functional dilatation, caused by immaturity, which can clear up in uterus or which will simply require a careful follow-up during the post natal period. Vesicoureteral reflux may count for 10 to 33% of urinary tract dilatations. There are no pathological limit values clearly stated in literature: a pyelectasis can only be the expression of a normal anatomical variability, without features of disease. In creating a diagnostic protocol for the newborn with prenatal diagnosis of hydronephrosis, all these possibilities must be accounted for the risk of focusing on mechanical obstruction is to overestimate and over-treat children that will never obtain any benefit from a surgical procedure.