What distinguishes stress urinary incontinence from urge urinary incontinence?

• A. Stress: detrusor overactivity; Urge: urethral sphincter weakness/pelvic floor incompetence
• B. Stress: urethral sphincter weakness/pelvic floor incompetence; Urge: detrusor overactivity
• C. Stress: bladder outlet obstruction; Urge: infection
• D. Stress: neurogenic bladder; Urge: normal detrusor activity

Answer: (B)

The distinction lies in the underlying mechanism: stress incontinence results from urethral closure failure due to pelvic floor weakness and/or urethral sphincter incompetence, so leakage occurs when there’s a rise in abdominal pressure (like coughing or lifting). Urge incontinence, on the other hand, comes from detrusor overactivity, where involuntary bladder contractions during filling trigger a sudden urge to void followed by leakage. So the first pattern is a structural support problem causing leakage with effort, while the second is a bladder muscle overactivity problem causing leakage with urgency. Other patterns, like obstruction or infection or a neurogenic bladder, don’t describe these two mechanisms.