Urinary Incontinence - Causes, Types and Diagnosis
Urinary incontinence is the loss of ability to control the bladder, causing involuntary leakage of urine, a problem that affects millions of women around the world. In this article we explain the causes and types of urinary incontinence.
To understand why urinary incontinence arises we must first learn what the normal bladder and urethra are. The basics. Urine is produced by the kidneys drained by ureters, stored in the bladder and excreted through the urethra (see the illustration opposite).
The bladder is the organ responsible for storing the urine temporarily produced by the kidneys during the day. When the urine volume approaches 200-300 ml, the stretching of the bladder wall sends signals to the brain, causing uncomfortable feeling of need to urinate. The fuller the bladder is, the stronger is the signal.
The kidneys produce urine continuously draining small amounts toward the bladder. This means that we always have some amount of urine in the bladder throughout the day, even when we do not need to urinate. At times we can have up to 200 ml of urine stored in the bladder without realizing it.
But how do we prevent this stored urine from exiting the bladder when trying hard not to pee?
Bladder
When the bladder is empty or with a small volume of urine bladder nerves send signals to the brain reporting it. At this time, the bladder muscle is relaxed, thus facilitating the storage of urine from the kidneys. At the same time the brain controls the muscles around the urethra so that the same remain contracted. This contraction is involuntary and imperceptible. The end result is a low pressure in the relaxed bladder, and a high pressure in the constricted urethra, preventing the urine output.
The urethra is contracted by a group of muscles that make up the urinary sphincter or urethral sphincter. In the sphincter other muscles of the pelvic region also act by controlling the pressure on the urethra and keep it closed.
When the bladder is full, its dilation sends stimuli to the brain to urinate. At this point the process of closing the urethra begins to become less involuntary and hinge upon an active effort of the sphincter and pelvic muscles. At the same time the bladder muscle, called detrusor muscle, starts to reduce emptying the bladder. The fuller the bladder is, the greater is the pressure and the need to keep strength to hold urine.
When urinated the detrusor (bladder muscle) contracts, squeezing the bladder and expelling the volume of urine inside. Concomitantly, the urinary sphincter and pelvic muscles relax, opening the urethra and allowing the flow of urine.
Therefore, urinating and holding urine depends on the proper functioning of nerves and synchrony of muscle of the bladder and urethra.
Urinary incontinence is an extremely common, especially in women over 60 years. The biggest problem is the embarrassment, which in some cases may be so great that even the patient can't say it to the doctor. Although typically it affects older women, urinary incontinence can also affect young women and men.
The stress urinary incontinence is the one in which involuntary loss of urine occurs when there is an increase in intra-abdominal pressure, i.e. when we cough, sneeze, laugh, jump or when we make any effort to use the abdominal muscles. Increased abdominal pressure causes a rise in pressure in the bladder. In people with no problems, this pressure increase is not sufficient to overcome urinary sphincter, therefore, most individuals not lose urine efforts.
The urinary incontinence is caused in most cases by a muscle weakness in the pelvic region, causing a malfunction of the urinary sphincter, allowing the discharge of urine whenever there is a sudden increase in pressure within the bladder.
The stress urinary incontinence can be caused by pregnancy, pelvic muscle injury during vaginal birth by surgery in the pelvic area or the natural weakening of the muscles over the years.
Urge urinary incontinence
Urge incontinence
The urge urinary incontinence is the one that occurs by an overactive bladder, the bladder muscle contracts. The bladder has sudden contractions, causing urgency to urinate, which in some cases, often makes the patient urinate before having time to get to the bathroom. This type of incontinence is also called overactive bladder.
The urge incontinence may occur due to aging bladder, drop in estrogen levels (menopause), neurological diseases such as Parkinson's, urinary tract infection and other causes enumerated below.
Mixed urinary incontinence
Mixed urinary incontinence is the one that has characteristics of both types of incontinence mentioned above, i.e., a sphincter disfunction combined with a bladder which involuntarily contract. It is actually the most common presentation of urinary incontinence.
Urinary incontinence overflow
Overflow incontinence
The overflow incontinence is the one which occurs at the exit of urine obstructions, causing the bladder remain constantly full. Unlike other types of incontinence, this case is more common in men, especially those with prostate disease, whether benign hyperplasia, or prostate cancer. The growth of the prostate compresses the urethra and the bladder causes obligation to handle large volumes of urine. When the bladder is very, very full, the liquid pressure is so high that it overcomes the resistance caused by the prostate, so that the patient has no control of the time it's urinating.
People with diseases that cause damage to the nerves or muscles of the bladder also have difficulties in emptying it, and may have overflow incontinence.
Whatever the cause is, the initial mechanism of incontinence is always the same, overactive bladder, underactive bladder, obstructing the passage of urine or an incompetent urinary sphincter. It should be noted that it is very common for patients with urinary incontinence to have more than one mechanism at the same time.
There is also urinary incontinence due to inability of the patient, as in cases of severe neurological damage and dementia.
Below, we will mention the diseases and conditions that most commonly lead to urinary incontinence.
The initial evaluation of urinary incontinence includes an assessment of the patient's clinical history and a simple urine test. The doctor also usually does tests like asking the patient to cough or push abdomen to visually identify the leakage of urine.
The urodynamic test can also be used for evaluation of incontinence. The test is done by inserting a catheter through the urethra and bladder for measurement of pressure in the bladder with different volumes of liquid. Thus it is possible to know if the bladder supports normal volumes of urine.
An ultrasound of the bladder can also be used for signs of obstruction and the ability of the bladder to be emptied completely.
