Congenital hydronephrosis is caused by certain factors during fetal period causing ureteral dysplasia, or external compression, the main types are as follows: 1. UPJO stenosis, narrowing of ureteropelvic junction; 2. Stenosis at the entrance of the vesicoureter; 3. Vagal vascular compression, because the renal arterial blood supply is not exactly a single vessel, some vagal vessels are issued from other trunks and supply to the kidney locally, these vessels if across the ureter may compress the ureter during the development process, causing hydronephrosis in the kidney. When these three conditions occur, if the fluid buildup reaches a certain level, it may have to be resolved surgically. The surgical solution depends mainly on what kind of surgery is used, and more importantly, it is related to the surgeon, whether the surgery is open or lumpectomy, and the surgeon, whether the surgeon is skilled or not for the operation, and if it recurs, it may be the restenosis caused by the surgery itself. In addition, there may be a relationship with the patient’s constitution. If the patient is a scar patient, the lumen may have to be further narrowed because the scar is too large after surgery.