Hydronephrosis, also known as hydronephrosis, if left untreated will affect renal function as time lengthens, and in the end there is a possibility of renal failure and complete loss of renal function. Hydronephrosis is due to the obstruction of the urinary tract below the ureteral junction of the renal pelvis, the urine produced by the kidneys can not be discharged, the renal pelvis gradually enlarges, the pressure inside the kidneys gradually increases, the renal cortex gradually becomes thinner, the glomerular filtration function decreases, and impaired renal function occurs. If left untreated eventually the renal cortex becomes very thin and renal function is lost. Hydronephrosis is also prone to complicate infection and aggravate the damage of renal function. Therefore, hydronephrosis must go to the urology department of regular public hospitals to actively search for the cause of the disease and release the obstruction.