The inability to urinate (retention) is frequently caused by injury,
infection, or medications. You may urinate less when you are
dehydrated.
Retention occurs more frequently in men than in women and is often
caused by
prostate enlargement. Prostate enlargement develops
gradually; early symptoms include urinating in a small stream (incomplete
retention) and difficulty starting urination.
In both women and men, the inability to urinate occurs occasionally
after surgery or when there is a blockage of the
urethra. Problems with the structure or function of
the urinary tract, such as
vesicoureteral reflux or an obstruction in the urinary
tract (a blood clot or
bladder stone, for example) can also cause
retention.
The inability to urinate may also be a symptom of a serious problem,
such as
acute renal failure.
How quickly the inability to urinate develops may help determine the
seriousness of the symptom. Call your health professional if you are unable to
urinate.