Inability to empty the bladder completely or at all
- More common over the age of 50
- More common in males
- Genetics and lifestyle are not significant factors
Urinary retention may be either acute or chronic. In acute retention, the bladder cannot be emptied at all despite a desperate urge to do so, and a sudden and painful build-up of urine occurs. In chronic retention, some urine can be passed with difficulty, but the bladder cannot be emptied completely, and as a result a gradual and painless build-up of urine occurs. Both forms of urinary retention are more common in men.
What are the causes?
Anything that exerts pressure on the urethra (the tube from the bladder to the outside of the body) can restrict the flow of urine, causing acute or chronic urinary retention. The most common cause in men is an enlarged prostate gland. Sometimes, the flow of urine is restricted by a narrowed urethra (see Urethral stricture) or by a tightened foreskin of the penis (see Phimosis). In women, retention may occur during early pregnancy due to pressure by the enlarging uterus on the urethra, but it may disappear later as the uterus rises up into the abdomen. In both sexes, urinary retention may be caused by constipation because faeces in the rectum can press on the urethra. Rarely, the flow of urine from the bladder is restricted by conditions in which the neck of the bladder is obstructed, such as bladder stones and bladder tumours.
Damage to the nerves supplying the bladder muscles can also cause urinary retention. Damage may occur in disorders such as multiple sclerosis and diabetes mellitus, or it may be caused by spinal injury.
In some cases, chronic urinary retention can become acute because of a sudden increase in the amount of urine produced, which can be triggered by diuretic drugs, cold weather, or alcohol consumption. In other cases, acute urinary retention is a side effect of antidepressant drugs, drugs for Parkinson’s disease (see Parkinson’s disease and parkinsonism), or cold and flu remedies.
What are the symptoms?
Symptoms of acute urinary retention develop over a few hours and include:
A distressing and painful urge to pass urine without being able to do so.
A frequent urge to pass urine.
Swelling of the abdomen.
Difficulty starting to pass urine.
A weak flow of urine that ends in a dribble. In some cases, there may be involuntarily dribbling of urine between visits to the toilet.
In contrast to acute retention, chronic retention is unlikely to cause any pain, although the condition can be uncomfortable. The symptoms tend to develop more slowly and include:
Urinary retention can cause kidney damage if urine cannot drain from the kidneys (see Hydronephrosis).
What might be done?
If you have acute urinary retention, you will probably need to have your bladder emptied in hospital (see Bladder catheterization). You will have a rectal or pelvic examination and may later have special tests (see Urodynamic studies, and Cystoscopy) to identify the underlying cause.
Chronic urinary retention may be suspected if a routine medical examination reveals that you have an enlarged bladder. Diagnostic tests are the same as those for acute retention. The cause of the retention is treated if possible, and, in most cases, bladder function returns to normal. If the condition results from nerve damage, permanent or intermittent catheterization to drain the urine may be necessary. You may be taught how to catheterize yourself.
Urinary retention that occurs during pregnancy usually disappears when the uterus enlarges and moves up and out of the pelvis into the abdominal area, relieving pressure on the urethra.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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