What mechanical factors contribute to female stress urinary incontinence?

• A. Pelvic floor weakness.
• B. Urethral hypermobility.
• C. Intrinsic sphincter deficiency.
• D. Pelvic floor weakness and urethral hypermobility or intrinsic sphincter deficiency.

Answer: (D)

The key idea is that stress urinary incontinence in women mainly results from mechanical failures in supporting the urinary continence system. When you cough, sneeze, or strain, intra-abdominal pressure rises and urine leakage occurs if the urethral closure pressure can’t stay above that pressure. This can happen in a few ways: the pelvic floor and supportive tissues can be weak, which allows the bladder neck and urethra to descend and become hypermobile; or the urethral sphincter itself can be deficient, so it can’t close tightly even if the support is present. Both pathways can contribute, and they can occur together.

Therefore, the statement that pelvic floor weakness plus urethral hypermobility or intrinsic sphincter deficiency best captures the mechanical factors behind this condition, as it includes the major routes by which the urethra fails to stay closed during increased abdominal pressure. The other options list individual factors, but the comprehensive description accounts for the multifactorial mechanical nature of stress incontinence.