The residual urine volume of the bladder in normal adults is usually less than 10 ml. When the bladder residual urine volume is greater than 10 ml, an abnormal condition exists. In general, the common clinical cause of increased residual urine volume is bladder outlet obstruction, which is caused by prostatic hyperplasia, bladder neck sclerosis in women, and urethral stricture. The above-mentioned diseases usually cause obstruction of bladder urination, so that over time the residual urine volume in the bladder increases, and the increased residual urine volume tends to cause inflammation of the urinary tract, which further aggravates the condition. Therefore, when there is an increase in residual urine volume, it is important to conduct further tests to clarify the specific cause of the disease. Early treatment and intervention of the disease to pass urine and relieve excessive residual urine volume.