Stress incontinence

What is stress incontinence?

Urinary incontinence is the unintentional loss of bladder control. It is not a disease in itself, but a symptom of many different disease processes.

Stress urinary incontinence is the leakage of urine that occurs with physical exercise that increases abdominal pressure, such as coughing or sneezing. It is caused by loss of bladder neck and urethral support or inherent sphincter (valve) function.

Urinary incontinence affects women more frequently than men. It is far more common in the elderly, but should not be regarded as normal at any age. There is no single treatment for urinary incontinence. The treatment options will depend on the type and severity of the incontinence. Most patients with urinary incontinence can be cured or their condition can be improved.

What causes stress incontinence?

Stress incontinence is a bladder storage problem in which the strength of the muscles that help control urination is reduced. The sphincter is not able to prevent urine flow when there is increased pressure from the abdomen.

• Causes of stress incontinence in women
  • Hypermobility (increased movement) of the bladder neck and urethra related to the effects of childbirth
  • Urethral sphincter (valve mechanism) injury due to:
    • Childbirth
    • Trauma
    • Radiation
    • Previous surgery to the urethra or bladder neck
    • Thinning (atrophy) of the genital tissues related to the menopause
• Causes of stress incontinence in men
  • Urethral sphincter (valve mechanism) injury due to:
    • Transurethral resection of the prostate gland (surgery to the prostate gland via the urethra)
    • Radical prostatectomy (removal of the prostate)
    • Pelvic fracture
    • Radiation
    • Trauma

Risk factors

• Female sex
• Multiple childbirth
• Old age
• Pelvic radiation
• Pelvic surgery
• Pelvic trauma
• Tuberculosis of the urinary tract
• Stroke
  

Females are more prone to incontinence than males. The female urethra is short and the continence mechanism is less well developed than in the male. The female bladder neck and urethra are also much less well supported than in the male, and are subjected to the rigours of childbirth.

Multiple childbirths stretch and weaken the support of the bladder and urethra. This can cause increased movement of the bladder neck and the urethra, leading to stress urinary incontinence. Injury during childbirth or caesarean section can cause a vesicovaginal fistula (a hole between the vagina and bladder) to develop.

Bladder muscle instability is common in old age and can lead to incontinence. The menopause causes thinning of the vagina and urethra, which impairs the occlusive function of the urethra. Elderly men are prone to benign prostate enlargement, which can lead to chronic retention and overflow incontinence.

Tuberculosis of the urinary tract can lead to a small contracted bladder incapable of storing adequate amounts of urine. Trauma, surgery or radiation to the pelvis can either damage the bladder or urethra directly, or can damage the nerves that control bladder function. Almost any neurological disease can affect the control of bladder function. Strokes, dementia and spinal cord injuries commonly lead to incontinence.

What are the symptoms of stress incontinence?

In stress urinary incontinence the continence mechanism cannot deal with elevations in intra-abdominal pressure. The intra-abdominal pressure is transmitted onto the bladder, causing urine to leak from the urethra.

Activities like coughing, sneezing, lifting of heavy objects or getting up from a chair causes an increase in intra-abdominal pressure that is associated with leakage of urine. In very mild cases only a few drops of urine is lost with strenuous activity. In severe cases large amounts of urine can leak with moderate increases in intra-abdominal pressure.

How is stress incontinence diagnosed?

The diagnosis of urinary incontinence is made based on a medical history, a physical examination and some confirmatory special tests.

History and examination

A careful history will often indicate the type of incontinence. The voiding pattern is noted, and direct questions are asked regarding other urinary tract symptoms such as frequency or pain or discomfort during urination (dysuria). Any concurrent or previous medical, surgical or obstetric history is noted.

The bladder is examined to see if it is full or empty, and whether it is tender or not. A basic neurological examination is performed to rule out neurological causes for the incontinence. The underwear and pads are examined for evidence of wetness. The genital skin is inspected for evidence of inflammation. The urethra and vagina are examined next, usually with a speculum in place. The health professional specifically looks for atrophy of the tissues and for evidence of leaking with coughing. An assessment is made of the integrity of the bladder and urethral support. A urine sample is tested for evidence of infection and blood.

Special tests

Which special tests are performed will depend on the findings of the history and the physical examination, and the suspected cause of the incontinence. For stress incontinence special tests are not necessarily indicated. Most authors would confirm their clinical finding by urodynamic testing prior to embarking on surgery for these patients. Urodynamic testing should confirm a bladder and a low bladder outlet resistance. A micturating cysto-urethrogram is something performed to demonstrate bladder neck descent on straining.

How is stress incontinence treated?

Non-medical treatment

• Weight loss
• Stopping smoking
• Pelvic floor exercises - such as Kegel exercises, strengthens the muscles of the pelvic floor, thereby improving the urethral sphincter function.
• Vaginal weights
• Biofeedback - a method of positive reinforcement in which electrodes are placed on the abdomen and the anal area.
• Electrical stimulation

Non-medical treatment can be very effective in motivated patients with minor degrees of stress incontinence. The short-term results are often very good, but this is not always maintained in the long-term. Published studies quote cure/improvement rates of 50-80 percent for pelvic floor exercises.

Medical treatment

• Oestrogens
• Alpha-agonists
• Combination of the above

Medical treatment does not have a great role in stress incontinence. Post-menopausal atrophy affects the closure of the urethra. Alpha-agonists increase the tone in the bladder neck, thereby increasing outflow resistance. Some studies indicate a beneficial effect using a combination of oestrogen and an alpha-agonist in older women who have experienced menopause.

Surgical treatment

• Periurethral injections of bulking agents
• Suspension operations
• Sling operations
• Artificial urinary sphincters

Peri-urethral injections involve the injection of bulking agents into the urethra to improve effective urethral closure. Commonly used agents include fat, collagen,Teflon paste and silicon particles. Injection therapy is suitable for women with intrinsic sphincter deficiency rather that hypermobility, as well as for men with incontinence caused by prostate surgery. The major advantage of injection therapy is that it is a minor procedure. Short-term results are good, but often not maintained long-term.

The various suspension operations restore the normal anatomy in patients with hypermobility and improve the support of the urethra and the bladder neck. Open suspension operations such as the Burch suspension provide the best long-term results. The various needle suspensions have fallen into disuse due to high failure rates.

Urethral slings can be used in patients with intrinsic sphincter deficiency as well as those with hypermobility. It involves the placement of a strip of tissue or artificial substance that supports the urethra and bladder neck like a hammock. It increases outflow resistance and improves urethral closure by supporting the mid urethra. The vast majority of patients can be rendered dry this way, but the operation does carry the risk of difficulty with passing urine afterwards.

What is the prognosis?

Behavioural changes, pelvic floor exercise therapy, and medical management of stress incontinence usually improve symptoms rather than cure the disorder. Surgery may have a 75 - 95% cure rate when patients are carefully selected.

When to call your doctor

All but the most minor degrees of incontinence tend to be extremely inconvenient for the patient. Although incontinence per se is not detrimental to the physical well-being of the patient, it has a negative impact on the social, sexual, recreational and working lives of people. Thus anybody with a degree of incontinence that affects his or her lifestyle should see a health professional.

How can stress incontinence be prevented?

It is not possible to avoid all the potential causes of urinary incontinence. Obesity and smoking definitely make stress incontinence worse and reduce the success rate of surgery. Multiple vaginal deliveries weaken the pelvic floor and contribute to stress incontinence.

Performing Kegel exercises (tightening muscles of the pelvic floor as if trying to stop urine stream) may help to strengthen the pelvic floor muscles. Performing Kegel exercises during and after pregnancy can decrease the risk of developing stress urinary incontinence after childbirth.