Inability to Urinate
What Is an Inability to Urinate?
When you cannot empty your bladder completely, or at all, despite an urge to urinate, you have urinary retention. To understand how urinary retention occurs, it is important to understand the basics of how urine is stored in and released from the body.
The bladder is a balloon-like organ in the lower part of the belly (pelvis) that stores urine.
- Urine is composed of waste and water filtered from the blood by the kidneys.
- It travels down two thin tubes called ureters (one from each kidney) to the bladder.
- When about 1 cup (200 ml-300 ml) of urine has collected in the bladder, a signal is produced in response to the stretch of the bladder from the nerves located in the bladder wall. This signal is sent to the nerves in the spinal cord and the brain, and the brain then returns a signal that starts contractions in the bladder wall. At the same time, another signal is sent to the internal sphincter muscle to relax.
- These two reactions combined allow urine to flow out of the bladder and down a narrow tube called the urethra.
- From there, it is released from the body by urination (or micturition).
- To a certain point, urination can be voluntarily controlled. We are all familiar with the experience of having to urinate at an inconvenient time. When you "hold it in," you are squeezing a muscle called the external sphincter to keep urine in the urethra.
Urinary retention may be acute -- occurring suddenly -- one feels the need to urinate and cannot urinate at all even despite having a full bladder, or chronic, when one does not empty one's bladder completely. Chronic urinary retention is not painful. The amount of urine left behind to be considered chronic urinary retention is not well defined; some state that it is 300 cc (a little over an 8 ounce cupful), yet others state that it is >1000 cc (one liter). Urinary retention requires medical attention, sometimes hospitalization, for treatment, symptom relief, and detection of the underlying cause. Failure to treat the condition can lead to infections or damage to the urinary tract and kidneys.
Urinary retention is not an unusual condition, and it is more common in men than in women.
Medically Reviewed by a Doctor on 10/27/2016
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