Urinary Incontinence

written by Dr Loh Chit Sin on 6 April 2011

What is it?

It is the involuntary loss of control of urine which is objectively demonstrable and presents as a social and hygienic problem. It is a very common condition with a prevalence of between 8-34% in Western communities. A recent study of 1362 Malaysian women showed that up to 30% had experienced incontinence. Most patients with urinary incontinence suffer in silence because they are embarrassed to come forward or resigned to the mistaken belief that this was an accepted fact of life and part and parcel of growing old. The same study revealed that up to two thirds had never brought up their complaints to their doctors.

What are the causes?

A normal bladder can accommodate a significant volume of urine with no appreciable rise in pressure. Urine is prevented from leaving the bladder by the constant contraction of the sphincter (figure 1) which works like a tap. During urination, the bladder muscle contracts, raising the pressure inside the bladder and at the same time, the sphincter opens up to allow urine to leave the bladder. Incontinence can result from abnormal bladder contractions or a weak sphincter mechanism.

The causes of incontinence can either be transient or established. Transient causes are more common in the elderly and are readily treatable. These include delirium, urinary tract infections, restricted mobility resulting in an inability to get to the toilet on time, stool impaction and certain drugs. The established causes are the result of lower tract dysfunction the most common of which is genuine stress incontinence which occurs mainly in women. This usually occurs as a result of weakened pelvic floor muscles after childbirth . Although far less commonly, men may suffer from this type of incontinence as well when the sphincter (figure 1) is weakened. This usually occurs after surgery to the prostate gland for cancer or injury to the nerves controlling this sphincter. Abnormal bladder contractions that commonly cause incontinence occur in a condition called detrusor instability or the unstable bladder. The bladder muscle escapes volitional control and spontaneous contractions cause the urge to pass water long before the bladder fills to maximum capacity. When this contraction produces a pressure too great to control then urine leaks out and causes incontinence. Detrusor instability has been variously reported to occur in up to 10% of the population. It usually occurs in young to middle aged women or in the elderly especially after a stroke. The most common cause of incontinence in men is the enlargement of their prostate gland. This is a small walnut shaped gland located above the sphincter (figure 1). The enlarged gland causes obstruction of the bladder outlet requiring the bladder to push very hard to evacuate the urine. After a long time the muscle becomes abnormal and unstable bladder contractions occur to cause incontinence. In a minority of these patients the incontinence can be due to overflow as the bladder is overfilled past its capacity and leakage of urine past the normal sphincter occurs. Spinal cord injury represents another important cause of incontinence in Malaysia, which has received very little attention. A mixture of abnormal bladder contractions and a weakened sphincter produces the incontinence.

The most common cause of incontinence in children is nocturnal enuresis which is bedwetting. This occurs in 15% of 5 year old and declines to about 1% by the age of 15. The exact cause is not known but it is possible that a delay in maturation of the nervous system in control of the bladder. There are other more uncommon causes but they cause day time incontinence as well in most cases.

What are the symptoms?

As the name suggests stress incontinence occurs in response to physical stress. Depending on the degree of pelvic floor weakness the leak may occur in response to coughing or sneezing, jumping or jogging or lifting heavy objects. In severe cases the leak can occur with almost any daily activity. Patients with unstable bladders often have the urge to pass water despite the fact that their bladders are not yet full. They keep having to visit the toilet very often even at night. If for some reason they are delayed in reaching the toilet, then a urinary leak may occur.

Elderly men with prostate enlargements experience incontinence in a way similar to the patients with unstable bladders. In addition to an increased frequency of urination, they would also have a slow urinary stream.

What tests are available?

A bladder chart or voiding diary is a simple yet useful test that the patient can do in participation with the urologist. All that is required is a log of the dates, times and amounts of urine passed as well an indication of when the episodes of incontinence occur. This diary will be of great help to the urologist in reaching a diagnosis and forms a baseline to which future charts can be compared when treatment is instituted.

A urine test is most commonly done but rarely provides very much information except in the case of urinary tract infections. In the young an intravenous urogram is indicated to exclude abnormalities of development of the urinary tract. This is a series of X-rays taken after contrast is injected into a vein in the arm. An ultrasound of the kidneys may be done in selected patients to exclude kidney damage. The most useful test in the armamentorium of a urologist is the urodynamics study (figure 2). Urodynamics will provide an objective evaluation of the function of the lower urinary tract . This is a laboratory study done by inserting two very tiny tubes into the bladder as well as a balloon catheter into the rectum and measuring bladder and rectal pressures during artificial filling of the bladder with saline. Bladder pressures are usually low and steady during filling of the bladder and any abnormality of pressures during this filling will be recorded and not only the diagnosis confirmed but also the magnitude of the disorder can be evaluated. In patients with spinal cord disorders the pressures measured during filling can be used to predict the risk of future kidney damage as well, thus it is particularly mandatory in these patients. The patient will be asked to void during this test to measure voiding pressures as well and these pressures are useful in the evaluation of obstruction to the bladder outlet. Urodynamics studies can also be useful in an attempt to more accurately tailor the type of treatment that should be employed for the particular patient.

 What treatment is available?

There are many varied types of treatments available and up to 80% of incontinence is curable. The cornerstone of good treatment is an accurate diagnosis. Your urologist using the relevant tests as previously described will decide this.

Children with nocturnal enuresis will benefit from general measures like restricting fluids after dinner, voiding before bed and waking the child up to pass water before the parents retire. Alarms that detect the passage of small amounts of urine and wakes the child are useful as well (figure 3). There are also drugs which the urologist can employ as well. Patients with stress incontinence from a weakened pelvic floor can improve significantly by doing simple pelvic floor exercises or use devices like vaginal clones (figure 4) or biofeedback equipment. They work by exercising the pelvic floor muscles thus returning them to their natural tone that will support the urethra during physical stress. There are even devices that provide electrical stimulation of the pelvic floor that will increase muscle tone as well. The more general measures will include loosing weight and avoiding tight fitting clothes. These conservative measures are effective with younger patients with mild degrees of stress incontinence. For patients with more severe stress incontinence, surgery is the main recourse. The aim of the various surgical techniques is to support the urethra or the pelvic floor on which the urethra sits. This is done variously by stitching the pelvic floor upward to the abdominal wall or the pubic bone. In patients with severe stress incontinence a sling is passed under the urethra and used to support the bladder neck and urethra to the abdominal wall or pubis. New and less invasive surgeries, such as injections of collagen or synthetic particles into the urethra (figure 5) had been developed recently. These procedures work by increasing urethral resistance. Most cases of sphincter weakness incontinence in men are only satisfactorily treated by the insertion of an artificial urinary sphincter (figure 6).

As for the unstable bladder, medications are the mainstay of treatment as well as a self-administered plan of bladder training. Even paralysed patients from spinal cord injuries can achieve continence by simple manoeuvres like clean intermittent self catheterisation. In this procedure the patient inserts a clean catheter in to his/her urethra to empty his bladder and maintain continence. A variety of surgical procedures, some including the use of the artificial urinary sphincter (figure 6), can be highly successful. The bottom line is that continence can be achieved in most situations if proper urological consultation is sought.