Definition Bladder outlet obstruction is a condition in which the opening between the bladder and the urethra is partially or completely blocked. This allows only some urine, or sometimes none at all, to empty from the bladder.
What is going on in the body? When the flow of urine is first blocked, the bladder responds by thickening the bladder wall and squeezing harder to push urine out. But if the blockage lasts a long time, the bladder begins to fail and the bladder wall thins out.
What are the signs and symptoms of the condition? In some men, the bladder outlet is obstructed by an enlarged prostate caused by prostate cancer or benign prostatic hyperplasia. Symptoms, which begin slowly and progressively get worse, may include:
trouble starting the urinary stream
a weak urinary stream
frequent urination during the day
getting up at night to urinate, a condition called nocturia
urinary urgency, or feeling the need to urinate right away
meatal stenosis, or narrowing at the point that the urethra reaches the outside of the body
In these cases, symptoms have a slower onset. The force of the urinary stream slowly weakens, and there may be blood in the urine.
bladder stones, which often form if the bladder outlet is obstructed, can worsen the condition. This usually causes a sudden, very painful blockage of urine.
What are the causes and risks of the condition? Bladder outlet obstruction is rare in women. But, when its does occur, it is usually caused by neurological disorders or a very large, sagging bladder. Bladder outlet obstruction is very common in older men. It is usually caused by an enlarged prostate from benign prostatic hyperplasia or prostate cancer.
Other causes, which are also more common in men, include:
physical defects of urethra, which are usually present at birth
cancer of the urethra
All men, as long as they still have their testicles and are producing testosterone, develop some degree of enlarged prostate as they get older. Prostate cancer is also very common. People who smoke and are exposed to certain chemicals are at increased risk of developing bladder tumours and urethral cancer. Urethral strictures can occur as a result of prior surgery or recurrent episodes of urethritis, an infection of the urethra.
What can be done to prevent the condition? Cessation of smoking is advised to reduce the risk of bladder tumours and urethral cancer.
How is the condition diagnosed? A person with this condition sometimes has urine left in the bladder after urinating. When this amount is large, or if the person cannot urinate at all, the doctor can often feel the bulging bladder by touching the lower abdomen. The urine left in the bladder can be measured with an x-ray test known as ultrasound or by placing a tube, called a urinary catheter, in the bladder. Other tests that help the doctor determine the severity of the condition include:
uroflowmetry, which measures the rate of urine flow
pressure flow studies, which compare the pressure in the bladder with the flow of urine during voiding
What are the long-term effects of the condition? Bladder outlet obstruction can occasionally lead to a total breakdown of the bladder. If this occurs, the person is not able to void at all. In most cases, bladder outlet obstruction is important only in as much as it affects the person's quality of life. But the cause of this condition can be important. If it is caused by prostate cancer, bladder tumour, or urethral cancer, the cancer must be treated right away before it spreads to other parts of the body.
What are the risks to others? There are no risks to others.
What are the treatments for the condition? A person who has urine left in the bladder after voiding or who cannot urinate at all needs to have the urine drained from his or her bladder. This can be done two ways:
by placing a urinary catheter through the urethra and into the bladder
by passing a tube, called a suprapubic cystostomy, through the skin of the lower abdominal wall into the bladder
These drains may be left in for a while.
The cause of the bladder outlet obstruction also will need to be treated.
What are the side effects of the treatments? The tube used to drain the urine can cause discomfort and make the person with the condition feel like he or she needs to urinate. A urinary catheter or suprapubic cystostomy that is left in the bladder requires a cumbersome drainage apparatus. It can also cause irritation where it exits from the body.
What happens after treatment for the condition? After treatment, a person should watch for urinary symptoms, such as a weak urinary stream. This might indicate a recurrence of the disease or a failure of the procedure.
How is the condition monitored? Symptoms should be monitored by the person. The underlying cause may warrant regular visits to the doctor.
Author: Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 19/05/2005 Contributors Potential conflict of interest information for reviewers available on request
