Urinary Incontinence - Causes and Treatment
Urinary incontinence is the involuntary loss of urine. It is not a disease in itself, but can be a symptom of many different disease processes.
The functions of the bladder are to store and expel urine under appropriate circumstances. During voiding, the bladder muscle contracts while the sphincter relaxes in a coordinated fashion. The bladder neck and sphincter (valve) prevent urine from leaking.
The main types of urinary incontinence are:
- Stress urinary incontinence: urine leakage associated with episodes of increased intra-abdominal pressure such as coughing or sneezing.
- Urge incontinence: characterised by a great desire to urinate, which cannot be suppressed. This is associated with symptoms of urgency and frequency.
- Overflow incontinence: associated with chronic retention of urine, a weak urine stream and difficulty passing urine.
- Total incontinence: the continuous leakage of all the urine.
The causes of urinary incontinence vary depending on the type of incontinence.
In stress urinary incontinence, the continence mechanism cannot deal with raised pressure in the abdomen. This pressure is transmitted onto the bladder, causing urine to leak from the urethra. This may be caused by:
- In women, hypermobility (excessive mobility)of the bladder neck and urethra, related to the effects of childbirth
- In females, urethral sphincter (valve mechanism) dysfunction, which may be related to childbirth injury; trauma; radiation; previous surgery to the urethra or bladder neck; or atrophy of the genital tissues related to the menopause
- In males, stress urinary incontinence may be caused by urethral sphincter (valve mechanism) injury due to prostate surgery; pelvic fracture; radiation or trauma .
Urge incontinence (males and females) is caused by the inability of the bladder to store adequate amounts of urine for long enough between voiding. This may be due to:
- Detrusor (bladder muscle) instability due to old age; cystitis; radiation; bladder stones; bladder tumours or unknown causes.
- Small capacity bladder due to interstitial cystitis; tuberculosis of the bladder; schistosomiasis (bilharzia) of the bladder; radiation or neuropathic bladder
In overflow incontinence, the bladder is permanently full and distended with urine. The kidneys continue to produce urine, and the excess spills out of the urethra. This may be due to:
- Obstruction of the bladder outlet due to prostatic enlargement, prostate cancer or urethral strictures (narrowing). Such obstruction is relatively common in elderly men but rare in females.
- Muscle dysfunction. Poor bladder contraction may be due to damage to its nerve supply by diabetes mellitus; pelvic surgery; low spinal cord injury; multiple sclerosis or stroke.
Total incontinence is usually due to abnormal communication between the urinary tract and the outside. This may be:
- A vesicovaginal fistula (abnormal connection between the bladder and vagina)
- A ureterovaginal fistula (abnormal communication between the ureter and vagina)
- An ectopic ureter: the ureter opens in an abnormal position (e.g. in the vagina). Depending on the location, it can cause incontinence in females. If only one side is affected the patient passes urine in the normal manner, while also suffering from a continuous leak. This is a congenital abnormality – the patient is born with it.
Stress urinary incontinence: Patients are usually dry while sitting still or lying down. Activities like coughing, sneezing, lifting of heavy objects or getting up from a chair cause an increase in intra-abdominal pressure and urine leakage. In very mild cases, only a few drops of urine are lost with strenuous activity. In severe cases, large amounts of urine can leak with moderate pressure increases.
Urge incontinence: There is a great desire to urinate that cannot be suppressed. The patient leaks urine before getting to a toilet. This is associated with the frequent passage of urine during the day (frequency) and night (nocturia). Bladder muscle instability caused by pathology such as infection, stones or tumour is often associated with burning urine (dysuria) and blood in the urine (haematuria). Bladder pain is common with infections, stones and interstitial cystitis.
Overflow incontinence: The bladder is chronically distended and permanently full of urine. The incontinence is usually a persistent low-level leakage, often worse at night. Patients are still able to pass urine, but only pass small amounts with difficulty. They often complain of a poor stream, straining while passing urine and a feeling of incomplete emptying.
Total incontinence: With large vesicovaginal fistulae, there is a constant leakage of all of the urine via the vagina. A patient with a tiny fistula may pass urine in the normal way, as well as suffer from a constant leak from the vagina. With a ureterovaginal fistula, urine from the kidney on the affected side will continuously leak out. If the opposite ureter and the bladder are normal, the patient will pass the urine coming from that side in the normal manner.
Urinary incontinence affects about 5% of the population – 8% of females and 3% of males. It is more common in old age and in debilitated patients. Approximately 50% of all nursing-home residents, as well as 15-30% of women over age 65 in retirement communities, suffer from it. Despite being more common in old age, incontinence should not be regarded as "normal" at any age.
- Female sex: 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.
- Multiple childbirths stretch and weaken the support of the bladder and urethra. This can cause hypermobility of the bladder neck and the urethra, leading to stress urinary incontinence.
- Injury during childbirth or caesarian section can cause a vesicovaginal fistula to develop.
- Old age. Detrusor (bladder muscle) instability is common in old age and can lead to urge incontinence.
- Menopause causes atrophy of the vagina and urethra, which impairs the ability of the urethra to close.
- Elderly men are prone to benign prostatic enlargement, which can lead to chronic retention and overflow incontinence.
- Pelvic trauma, surgery or radiation to the pelvis can damage the bladder or urethra directly, or can damage the nerves that control bladder function.
- Tuberculosis of the urinary tract can lead to a small, contracted bladder incapable of storing adequate amounts of urine.
- Almost any neurological disease can affect the control of bladder function. Strokes, dementia and spinal cord injuries commonly lead to incontinence.
When to see a doctor
Although incontinence per se is not detrimental to the physical well-being of the patient, it tends to be extremely inconvenient, and impacts negatively on one’s social, sexual, recreational and working life. The majority of incontinent patients can either be cured or markedly improved.
Anybody with a degree of incontinence that affects his or her lifestyle should see a health professional. Patients with blood in the urine, bladder pain or burning urine should seek help promptly, in case the incontinence has a serious underlying cause.
Diagnosis of urinary incontinence is based on a medical history, a physical examination and some confirmatory tests.
- The doctor will take a detailed history, noting the type of incontinence and its severity. The voiding pattern is noted, and questions are asked regarding other urinary tract symptoms such as frequency or dysuria. Any medical, surgical or obstetric history is noted.
- During the physical examination, the urethra and vagina may be inspected, usually with a speculum. The health professional specifically looks for atrophy of the tissues and for evidence of leaking with coughing. A rectal examination may also be done.
- The bladder is examined to see if it is full or empty, and whether it is tender. An assessment is made of the integrity of the bladder and urethral support.
- A basic neurological examination will rule out neurological causes. Underwear and pads are examined for wetness. The genital skin is inspected for urine-induced dermatitis.
- A urine sample will be required, so it is best not to empty the bladder immediately before the visit to the doctor. The sample is tested for evidence of infection, blood or underlying bladder pathology (stone, tumour etc). If there is an underlying cause of bladder instability, this should be diagnosed and treated first.
In a classic case of stress urinary incontinence, without urinary urgency or frequency, further tests may not be necessary. However, depending on the doctor’s findings, special tests may be done:
- Ultrasound scan - This uses very high frequency sound waves to obtain images of the kidneys and bladder. This will show obstruction, incomplete emptying, or a large bladder volume after the patient has tried to pass urine.
- Intravenous pyelogram (IVP) - Contrast medium is injected into a vein and excreted by the kidneys. X- rays are taken while the contrast passes through the urinary tract. An IVP can demonstrate abnormal anatomy e.g. ectopic ureter.
- Micturating cystourethrogram (MCUG) - Contrast medium is inserted into the bladder. X- rays are taken when the bladder is full and while the patient passes urine. In the case of a vesicovaginal fistula , a MCUG will show contrast leaking from the bladder into the vagina.
- Urodynamic study - This is a functional test of bladder muscle and bladder outlet function. Most specialists will confirm their clinical findings by urodynamic study before embarking on surgery. Pressure probes are inserted into the bladder and the rectum. During the initial filling phase, the bladder capacity and response are measured. Then the patient is asked to pass urine, and bladder pressure, contraction and outlet resistance are measured.
- Cystoscopy - This is the visual inspection of the inside of the urethra and bladder with a special instrument. It can show abnormal anatomy, e.g. ectopic ureter, and can define the exact position and size of a fistula. Along with a digital rectal examination, cystoscopy can confirm a diagnosis of obstruction due to an enlarged prostate or urethral stricture in men.
Most patients with urinary incontinence can be cured or improved. Treatment varies according to the cause, type and severity of the problem.
In motivated patients with minor stress incontinence, non-medical treatments can be very effective. Short-term results are often very good, but this is not always maintained in the long term.
Such techniques may include:
- Weight loss
- Stopping smoking
- Pelvic floor exercises
- Vaginal weights
- Electrical stimulation
- Drug treatment does not play a great role in stress incontinence. However:
- Oestrogens can be taken orally or applied locally. These restore the bulk of urethral tissue affected by postmenopausal atrophy, leading to better closure of the urethra.
- Alpha-agonists increase the tone in the bladder neck, increasing outflow resistance.
- A combination of oestrogen and an alpha-agonist in older post-menopausal women may be beneficial.
There are surgical treatments for stress incontinence:
- Periurethral injections involve the injection of bulking agents (eg. fat, collagen, Teflon paste or silicon particles) into the urethra to improve closure. This is suitable for women with sphincter deficiency, as well as for men with post-prostatectomy incontinence. The major advantage is that it is a minor procedure. Short-term results are good, but often not maintained long-term.
- Suspension operations restore normal anatomy in patients with hypermobility and improve the support of the urethra and the bladder neck; however, these procedures have fallen into disuse due to high failure rates.
- Urethral slings involve the placement of a strip of tissue or artificial substance to support the urethra and bladder neck like a hammock. This increases outflow resistance and improves urethral closure. The vast majority of patients can be rendered dry in this way, but the operation does carry the risk of difficulty with passing urine; infection; or erosion of the artificial sling material, which then has to be removed.
- An artificial urinary sphincter (AUS) made of silicone can be used in someone with total incontinence resulting from irreparable damage to the sphincter. An AUS is very effective, but it is quite expensive, and there is a risk of infection or erosion of the synthetic material.
- Urge incontinence treatment may include:
- Non-medical treatment such as bladder training. Voiding by the clock and progressively increasing the time between voids can improve symptoms of patients with otherwise normal bladders. This can be combined with biofeedback and pelvic floor exercises.
- Drug therapy forms the mainstay of treatment for incontinence due to bladder instability. Medications such as oxybutynin, tolterodine and imipramine relax the bladder muscle and increase bladder capacity. Side effects include dry mouth, constipation and blurred vision.
- Injection of botulinum A toxin (Botox) into the bladder muscle can be used if the urge incontinence is due to a neurological disease causing overactive bladder contractions.
- Tiny bladders due to radiation or tuberculosis can be enlarged surgically. (A segment of intestine is patched onto the bladder.) Patients with intractable bladder instability who have failed medical treatment can also be treated in this way.
Overflow incontinence may be treated by:
- Surgically alleviating any bladder outflow obstruction – for example, removing all or part of an enlarged prostate gland.
- Intermittent self-catheterisation, if the incontinence is due to failure of the bladder to contract. Permanent catheters should be avoided if possible.
- Total incontinence due to a vesicovaginal fistula or ureterovaginal fistula is treated by surgical repair.
It is not possible to avoid all the potential causes of urinary incontinence. However, 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. (However, caesarian section carries its own set of risks.) Regular pelvic floor exercises reduce the incidence of post-partum incontinence.
Bladder training can be very effective in patients with urgency and frequency, and may arrest symptoms before urge incontinence develops.
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