Ureteral stones with hydronephrosis can cause fever, which may cause obstruction of the ureter, leading to infection in the kidneys. Ureteral stone in the process of downward movement, because the ureter has three narrowing, may be stuck in these three narrowing, causing ureteral obstruction, resulting in urine can not be discharged, it will cause hydronephrosis, the presence of hydronephrosis for a long time, may induce infection, due to the inflammatory substances can not be discharged, it will cause fever. If this condition is left untreated for a long time, it may cause some serious complications, such as septicemia, which may cause damage to the structure and function of the kidney, and may lead to renal failure. Therefore, when the above situation occurs, it is necessary to consult a doctor for examination and treatment as soon as possible to avoid causing serious complications.