Stress urinary incontinence and pelvic floor support
Stress urinary incontinence is urine leaking when pressure in the abdomen rises, because a weak pelvic floor (the muscles closing the bottom of the pelvis) fails to support the urethra.
Remember
Urine that leaks on coughing, laughing or lifting, without a sudden urge to pass it, is stress incontinence: weak pelvic floor support fails to keep the urethra closed when abdominal pressure rises.
Stress urinary incontinence (SUI) means urine leaks when the pressure inside the abdomen rises, for example with coughing, sneezing, laughing or lifting. The word stress means physical pressure, not emotional stress.
Normally the pelvic floor, the sling of muscles closing the bottom of the pelvis, supports the bladder neck (where the bladder joins the urethra) and the urethra (the tube that carries urine out). A well-supported urethra stays closed, so the intra-abdominal pressure (the pressure inside the abdominal cavity) is resisted and no urine escapes.
If the pelvic floor muscles are weak or damaged, the urethra is inadequately supported, and a damaged urethral sphincter (the ring of muscle that keeps the urethra closed) cannot hold the urethra shut when abdominal pressure rises. When pelvic floor support is weaker, the bladder neck and urethra become more mobile and drop downwards, the pressure is not resisted, and urine leaks. The bladder muscle itself is not the problem, so the leak is set off by effort and not by a sudden urge to pass urine.
Vaginal childbirth is a classic cause, because the baby's head stretches the structures of the pelvic floor. Increasing age and oestrogen deficiency (a fall in oestrogen, usually due to the menopause) are also risk factors.
Management starts with pelvic floor muscle training, regular squeezing exercises that strengthen these muscles. If that does not help, surgery can be considered, such as a sling (a supportive strip placed under the urethra).
Key facts
- Typical story
- urine leaks when pressure in the abdomen rises, for example on coughing or laughing, without a sudden urge to pass urine.
- Mechanism
- weak pelvic floor muscles or a damaged urethral sphincter cannot resist the pressure.
- Risk factors
- increasing age, oestrogen deficiency (usually due to the menopause), pregnancy, vaginal childbirth and obesity.
- Not the same as
- urge incontinence follows overactivity of the detrusor (the bladder wall muscle), and overflow incontinence follows a bladder that cannot empty fully.
- Management
- pelvic floor muscle training first; if that does not help, surgery such as a sling procedure can be considered.
Exam traps
- Involuntary contractions of the detrusor (the bladder wall muscle squeezing when it should be relaxed) cause urge incontinence, an overactive bladder, in which the leak follows a sudden, intense urge rather than coughing or lifting.
- An abnormal channel between the bladder and the vagina (a fistula) produces constant leakage, called total incontinence, rather than leakage only when abdominal pressure rises, so weak pelvic floor support does not explain it.
- A blocked urinary outflow stops the bladder emptying fully, so it stays overfull and leaks, which is overflow incontinence; that leakage tends to be frequent and is linked to poor emptying rather than to moments of raised abdominal pressure.
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