What causes stress urinary incontinence?

If you have noticed that you leak urine when you cough, sneeze or jump, you’re not alone - stress urinary incontinence is a form of urinary incontinence that affects many women. Although you might think this condition is only prevalent in older women, more than 50% of women with urinary incontinence are under the age of 50!

Definition:

Complaint of involuntary loss of urine on effort or physical exertion including sporting activities, or on sneezing or coughing.

What causes stress incontinence?

With normal bladder function, during the day, the pressure at the urethra (where the urine passes out) remains higher than the pressure at the bladder. When it comes time to go to the toilet and empty the bladder, the bladder contracts and the urethra relaxes. This causes the bladder pressure to overcome the urethral pressure, and the bladder can empty.

Stress incontinence comes about when there is difficulty keeping the urethral pressures high enough to counter the elevated bladder pressures that occur with activities such as coughing, jumping and skipping.

What causes low urethral pressures?

Muscle weakness:

Weakness to the pelvic floor muscles, whether this be from trauma, nerve damage or reduced muscle strength can be implicated in stress incontinence. Contraction of the pelvic floor muscles tensions tissue that sits behind the urethra and creates a firm support or a backstop. When we cough or jump, the pressure generated in the abdomen is transferred to the bladder, but also to the urethra. When there is firm support or backstop behind the urethra, this extra pressure can actually help close the urethra shut.

You can liken it to a hose running water. If it is sitting on the ground and you step your foot on it, the hose will kink and the water will stop running. If the hose was on the trampoline, when you step on it, the trampoline is not firm enough and the hose doesn’t kink, the water can still travel through.

If the muscles of the pelvic floor are weak, and cannot create tension in the tissue behind the urethra, the urethral pressures remain low, and leaking can result.

Tissue damage:

Sometimes, it is the tissue behind the urethra that is damaged. The muscles may be strong, but the tissue can no longer be tensioned. The pressure no longer can shut the urethra, as there is no firm backstop.

Reduced Oestrogen:

The urethra is filled with oestrogen receptors and lack of oestrogen directly affects the function of the urethra. In times of reduced oestrogen (menstrual cycle, menopause, breastfeeding), urethral pressures are affected which can cause stress incontinence. 

Urethral sphincter weakness:

The small muscles that surround the urethra can contract to help increase urethral pressures and maintain continence. 

Summary

We hope this gives you more of an understanding as to why you might leak when you cough, sneeze or jump. The next step is to ask for help! Treatment can consist of strengthening exercises, medications to pessaries or surgery. Contact your local GP or womens health physiotherapist for assessment and direction for treatment.