Reasons for not being able to urinate: 1. If a man has prostatic hyperplasia, he may have difficulty urinating. When prostatic hyperplasia develops to an extremely serious degree, he will be unable to urinate at all. Patients will have an obvious feeling of suffocation, accompanied by difficulty in urination or inability to urinate. They need to go to the hospital for examination, where they can touch the boundaries of a full bladder in the lower abdomen, perform a residual urine examination, and find a large amount of urine retention, which is confirmed to be caused by prostatic hyperplasia and needs to be treated with an indwelling catheter. 2. If there is urethral stricture, urethral trauma or urethral tumor, stones, etc. causing urinary obstruction, they can appear to be unable to urinate. The boundary of the filled bladder can also be touched in the lower abdomen, or urethroscopy is needed to confirm the presence of strictures, stones, tumors and other lesions. 3. Patients suffering from acute cystitis or urethritis can experience frequent urge to urinate, but each time the volume of urine is very small or they cannot pass urine because the inflammatory reaction of the mucosa of the bladder urethra, such as congestion and edema, causes increased irritation, and there is not much urine in the bladder to A strong desire to urinate arises, but you are unable to urinate because the urine volume is too small. In this case, the boundaries of the bladder are usually not palpable in the lower abdomen, and residual urine ultrasound is performed, often <50 ml or less, requiring anti-infection treatment.