Acute urinary retention is a symptom of sudden inability to urinate with a full and distended bladder. The clinical manifestations are painful symptoms such as fullness and distension of the lower abdomen, distress to urinate, inability to urinate, and tossing and turning. Causes: Acute urinary retention is one of the most common emergencies in urology, which requires urgent diagnosis and timely treatment because of its rapid onset and patient suffering. Urethral obstruction: It is caused by obstruction of the urethra due to inflammatory edema or stones, urethral stricture, urethral trauma, prostate hypertrophy or tumor. According to the etiology, there are two types of mechanical obstruction and dynamic obstruction. The mechanical obstruction includes sudden obstruction by urethral injury or stone, foreign body or prostatic hyperplasia, urethral stricture, etc. Dynamic obstruction includes acute injury to the central and peripheral nerves, inflammation, disease edema bleeding, various smooth muscle relaxation drugs such as atropine, prudence, etc. ②Neurological factors: various causes of plant nerve damage can cause urinary retention. Examination: painful symptoms such as fullness and distension in the lower abdomen, distress to urinate, desire to urinate, and tossing and turning. Mechanical obstruction of the urethra, any obstructive lesions of the bladder neck and urethra, power obstructive bladder, urethra and no organic obstructive lesions, various causes etiology caused by low blood, various causes etiology caused by low blood potassium: such as aldosteronism, diarrhea, long-term application of diuretics, etc., can make the bladder force urinary muscle incompetent, urinary difficulty or even urinary retention occurs.