Clinical meaning
Urinary incontinence is defined as the involuntary loss of urine that is objectively demonstrable and constitutes a social or hygienic problem. It affects an estimated 25-45% of women and 5-15% of men, with prevalence increasing significantly with age. Despite its high prevalence, incontinence is underreported because patients feel embarrassed or believe it is a normal part of aging - it is NOT. Normal continence requires intact anatomy and coordinated neurological control. The bladder detrusor muscle must relax during filling (parasympathetic inhibition, sympathetic activation via beta-3 receptors), allowing the bladder to store 300-500 mL of urine at low pressure. The internal urethral sphincter (smooth muscle at the bladder neck, sympathetic alpha-1 control) and external urethral sphincter (striated muscle, somatic pudendal nerve control) maintain closure pressure exceeding intravesical pressure. During voiding, parasympathetic activation (S2-S4, acetylcholine on muscarinic M3 receptors) contracts the detrusor while the sphincters relax coordinately. Stress urinary incontinence (SUI) is the involuntary urine loss with effort, physical exertion, sneezing, or coughing. It results from weakness of the pelvic floor muscles and/or urethral sphincter mechanism, allowing urethral closure pressure to be...