If you can’t urinate, then the possible causes: First, if you are a man, the most common is prostate hyperplasia, then there can be obstruction of the urethra, urinary difficulty or inability to urinate. Patients have a history of chronic urinary weakness or urinary effort, which leads to qualitative changes from quantitative changes, and eventually develops into inability to urinate. Ultrasound examination of the prostate gland and determination of residual urine are needed, and catheterization is given after diagnosis. Second, acute urethritis or cystitis, because the bladder and urethral mucosa congestion and edema, increased sensitivity, a little urine can stimulate a strong sense of urination, the actual bladder urine is not much. It is just this sensation of irritation that causes the patient to repeatedly go to urinate with little or no urine or inability to urinate. Need to carry out residual urine ultrasound measurement, such as residual urine is less than 50ml or less, the urine contains a large number of white blood cells, bacteria, the diagnosis of urinary tract infection caused by the inability to urinate. Third, if there is urethral stenosis, urethral stones and other lesions, can lead to complete obstruction of the urethra, the patient can not urinate, residual urine ultrasound measurement shows that a large amount of urine stored in the bladder. Urethroscopy is performed to visualize stones or strictures, resulting in urethral atresia. Urethral dilatation or urethroscopic lithotripsy is required to clear the urethra, and normal urination can be restored.