There are different causes of hydronephrosis in men, and the causes are different, the harm is also different. The following specific analysis: 1, inflammation caused by hydronephrosis, such as perirenal inflammation. If the patient has perinephric inflammation caused by hydronephrosis, then the patient can have fever, back pain and other symptoms, if not given timely antibacterial anti-inflammatory treatment, the inflammation is not effectively controlled, resulting in abscess, and then bacteremia, sepsis and other serious bacterial infections, or even life-threatening.2, male hydronephrosis is due to urinary tract obstruction and other reasons, such as enlarged prostate, etc. The male prostate, can be different causes. Prostate hypertrophy in men can cause hydronephrosis with symptoms such as frequent urination, incomplete urination, painful urination, etc. If not treated in time, it will cause renal function damage, which will result in renal atrophy, reduced renal blood flow, renal failure, and even uremia.