Normally, a woman’s bladder retains 0 to 10 milliliters of urine after urination. The most accurate way to measure the amount of urine left in the bladder is to catheterize the bladder after urination, which is an invasive procedure and is now often performed with ultrasound. In women, some urine remains in the bladder after urination, usually 0-10 ml. If the residual urine volume is greater than 20 ml, it is called increased residual urine volume. It can be seen in lower urinary tract obstruction, bladder forced urinary muscle contraction dysfunction and other diseases. Lower urinary tract obstruction such as urethral stricture, urethral stones and other conditions. The cause of bladder detrusor contractile dysfunction is more complex. Overactivity of the detrusor muscle during the storage phase can lead to urinary frequency, urgency and urge incontinence. Women will retain 0-10 ml of urine in the bladder after urination. If the amount of residual urine increases, please seek medical attention.