hi doctor, my 2year old son has hydronephrosis of left kidney and left puj obstruction , he went for an ultra sound last week and the dilation of his left kidney now measures 1.85cm, this has been ongoing from b4 birth and he gets scans every few months but at the scan last week the sonographer said theres slight separation in his right kidney which is his healthy one, what does slight separation mean. im so worried as he has other health problems too? thanks, deborah