How long does hydronephrosis lead to renal necrosis depends on the individual patient’s condition. Severe hydronephrosis may cause renal necrosis in more than half a year in general, and a few patients may develop to renal necrosis within a few days. Some severe patients may cause irreversible damage to renal function about six months after the onset of the disease, eventually leading to renal necrosis; a few severe patients may develop to renal necrosis within a few days. Depending on the specific clinical need, the cure rate of single hydronephrosis is high. For hydronephrosis caused by congenital stenosis of the pelvic-ureteral junction, laparoscopic surgery can be used. If the hydronephrosis is caused by ureteral stones, ureteroscopic lithotripsy or percutaneous nephrolithotripsy can be used for larger stones. In addition, patients with hydronephrosis should pay attention to rest, avoid excessive work, eat a light, easy to digest, avoid spicy and greasy food, eat more fresh fruits and vegetables, and drink more warm water. Patients with hydronephrosis need to go to the hospital in time, improve the examination under the guidance of experts, clarify the condition and cause of the disease, and treat the symptoms.