Intravenous pyelogram hydronephrosis, in general, can be categorized into three degrees, which are mild, moderate and severe. Usually the mild degree of hydronephrosis is usually about 2-3cm separation of the renal collecting system. The moderate one is usually about 3-4cm separation of the renal collecting system. In severe hydronephrosis, which is usually shown by intravenous pyelogram, the kidney has no obvious structure and is severely damaged, which belongs to a more serious type. Intravenous pyelogram can effectively and clearly show the structure and morphology of the kidney as well as the renal pelvis, which can help to determine the state of the disease, and it is recommended to consult a professional doctor for the specific grading.