Patients who have hydronephrosis must be treated promptly because long-term hydronephrosis can lead to decreased kidney function, which can develop into uremia. Also known as hydronephrosis, hydronephrosis can cause more serious damage to the kidneys. If hydronephrosis lasts for more than 3 months, only 20% of kidney function remains; if it lasts for more than 6 months, kidney function will be basically lost, so hydronephrosis must be given timely treatment. The more common causes of hydronephrosis include kidney stones, pelvic ureteral junction stenosis, prostatic hyperplasia, gynecological tumors, and retroperitoneal fibrosis, etc. The causes of hydronephrosis caused by these diseases are different, so the treatment methods are different, but surgery is mostly used. If for some reasons, such as tumor metastasis, the time for surgery is missed, a DJ tube can be placed in the urinary tract to temporarily relieve the symptoms of hydronephrosis and prevent further pressure on the kidney.