(See also Control of Urination Control of Urination The kidneys constantly produce urine, which flows through two tubes (the ureters) to the bladder, where urine is stored (see Figure: Viewing the Urinary Tract). The lowest part of the bladder... read more .)
People may retain urine because bladder muscle contractions are impaired, the opening of the bladder is blocked (bladder outlet obstruction Urinary Tract Obstruction Urinary tract obstruction is a blockage that inhibits the flow of urine through its normal path (the urinary tract), including the kidneys, ureters, bladder, and urethra. Blockage can be complete... read more ), or there is a lack of coordination between bladder contraction and relaxation Control of Urination The kidneys constantly produce urine, which flows through two tubes (the ureters) to the bladder, where urine is stored (see Figure: Viewing the Urinary Tract). The lowest part of the bladder... read more of the muscle that closes the opening of the bladder (urinary sphincter). Urinary retention is more common among men because prostate enlargement such as that due to benign prostatic hyperplasia Benign Prostatic Hyperplasia (BPH) Benign prostatic hyperplasia (BPH) is a noncancerous (benign) enlargement of the prostate gland that can make urination difficult. The prostate gland enlarges as men age. Men may have difficulty... read more may cause narrowing of the channel that carries urine out of the body (urethra).
Drugs, especially those with anticholinergic effects, such as antihistamines and some antidepressants, can cause urinary retention in both men and women. Other causes include a hard lump of stool that fills the rectum and presses on the urethra (fecal impaction Complications Constipation is difficult or infrequent bowel movements, hard stool, or a feeling that the rectum is not totally empty after a bowel movement (incomplete evacuation). (See also Constipation... read more ) and neurogenic bladder Neurogenic Bladder Neurogenic bladder is lack of bladder control because of a nerve problem such as a stroke, spinal cord injury, or tumor. Uncontrollable loss of urine (urinary incontinence) is the primary symptom... read more in people with diabetes Diabetes Mellitus (DM) Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. Urination and thirst are... read more , multiple sclerosis Multiple Sclerosis (MS) In multiple sclerosis, patches of myelin (the substance that covers most nerve fibers) and underlying nerve fibers in the brain, optic nerves, and spinal cord are damaged or destroyed. The cause... read more , Parkinson disease Parkinson Disease (PD) Parkinson disease is a slowly progressive degenerative disorder of specific areas of the brain. It is characterized by tremor when muscles are at rest (resting tremor), increased muscle tone... read more , or prior surgery of the pelvis that damages bladder nerves.
Sometimes, people cannot urinate at all. In such cases, the bladder stretches very painfully over a few hours as it fills with urine and people have swelling in the lower abdomen.
More commonly, people are able to pass some urine but cannot completely empty their bladder. In such cases, the bladder slowly stretches without causing pain. However, people may have difficulty starting urination, a weak urine stream, or a sense that the bladder has not emptied completely. Because the bladder stays relatively full, people may sometimes have leakage of urine (overflow incontinence Overflow incontinence Urinary incontinence is involuntary loss of urine. Incontinence can occur in both men and women at any age, but it is more common among women and older people, affecting about 30% of older women... read more ), urinating at night (nocturia), or frequent urination Excessive or Frequent Urination Most people urinate about 4 to 6 times a day, mostly in the daytime. Normally, adults pass between 3 cups (700 milliliters) and 3 quarts (3 liters) of urine a day. Excessive urination can refer... read more . Because the retained urine can be a breeding ground for bacteria, people may develop a urinary tract infection Urinary Tract Infections (UTIs) read more .
If a person is unable to pass any urine, the diagnosis is clear.
In other cases, doctors try to see how much urine remains in the bladder after the person has urinated as much as they can. Immediately after the person urinates, doctors either insert a catheter into the bladder to see how much urine comes out or do ultrasonography of the bladder to measure the amount of urine present. The amount of urine left after urinating is called postvoid residual volume. If this volume is more than about half a cup (slightly more in older people), urinary retention is diagnosed.
Doctors do a physical examination, usually including a rectal examination. In men, the rectal examination can indicate whether the prostate is enlarged. In men and women, the rectal examination helps identify a fecal impaction. Doctors may take a sample of urine to test for infection. Blood tests and imaging tests may be needed to determine the cause of urinary retention.
If people cannot urinate at all, doctors immediately insert a thin rubber tube into the bladder (urinary catheter) to remove the retained urine and provide relief.
The cause of urinary retention is treated. Drugs that can cause urinary retention are stopped whenever possible. Men who have an enlarged prostate may need prostate surgery or drugs to shrink the prostate (for example, finasteride or dutasteride) or drugs that relax the muscles at the neck of the bladder (for example, terazosin or tamsulosin). People who have nerve problems that interfere with bladder contractions or function may need to use a catheter themselves periodically or have a catheter permanently placed. Occasionally surgery is needed to direct urine from the bladder away from the urethra and out of the body.