Suggest Treatment For Pelviectasis

My granddaughter just diagnosed with pelviectasis, she has had 2 ultrasounds and it has remained the same. She is small for her age but at 3 yrs very intelligent. Her size looks normal petite, could her size have something to do with this or does it occur before birth? She does not urinate a lot and we push fluids, never I ll and very active! Thanks...