Ultrasound diagnostic stone criteria 1. Stone criteria: multiple sections showing a mass of strong echogenicity greater than or equal to 4 mm in the renal pelvis and calyces, with or without acoustic shadowing. Wu Dogang, Department of Ultrasound, Anyang People’s Hospital, Anyang, China 2. Obstruction criteria: dilated renal pelvis combined with dilated renal calyces. Experts have explained this in detail: because of the different resolution of ultrasound instruments in different areas and in different units in the same area, positioning is reported as long as stones greater than or equal to 4mm are seen. In addition, for the diagnosis of pediatric hydronephrosis, unlike adults, the diagnosis of obstruction cannot be based on the separation of the renal pelvis alone; pediatric urinary tract obstruction should be in addition to the expansion of the renal pelvis and the expansion of the renal calyces. 3. The dilatation of the renal calyces is divided into: mild – the calyces become blunt, moderate – the calyces are pestle-shaped, and severe – the calyces are cystic. It is not possible to report hydronephrosis based on the separation of the renal pelvis alone, because the internal diameter of the separated renal pelvis in some infants is 8mm or even 15mm, and it remains the same on repeated reexamination, so experts propose the diagnostic criteria of simultaneous expansion of the renal pelvis and calyces.