Is grade2 hydronephrosis dangerous? My mom used to have kidney stones of about 12mm on right and 4mm on left. We went for checkup until she felt The pain..The Sonologist doctor told us that he could see the size of the stone because she have fluid on her kidney. We went to surgery doctor and he told us again that the stone has dissolved into small pieces after looking at the ultrasound result.Next to the urologist doctor again, he told us to take CT scan and we are planning to,. But I keep worrying to much.. Is hydronephrosis grade2 dangerous or an emergency? What is the treatment usually given to them? Please answer