Urinary Retention: Causes

What causes urinary retention?

Urinary retention can be caused by an obstruction in the urinary tract or by nerve problems that interfere with signals between the brain and the bladder. If the nerves aren’t working properly, the brain may not get the message that the bladder is full.

Even if you know that your bladder is full, the bladder muscle that squeezes urine out may not get the signal that it is time to push, or the sphincter muscles may not get the signal that it is time to relax. A weak bladder muscle can also cause retention.

Nerve Disease or Spinal Cord Injury

Many events or conditions can damage nerves and nerve pathways. Some of the most common causes are

 vaginal childbirth

 infections of the brain or spinal cord

 diabetes

 stroke

 accidents that injure the brain or spinal cord

 multiple sclerosis

 heavy metal poisoning

 pelvic injury or trauma

In addition, some children are born with nerve problems that can keep the bladder from releasing urine.

Prostate Enlargement: Benign Prostatic Hyperplasia

As a man ages, his prostate gland may enlarge. Doctors call the condition benign prostatic hyperplasia (BPH), or benign prostatic hypertrophy.

As the prostate enlarges, the layer of tissue surrounding it stops it from expanding, causing the gland to press against the urethra like a clamp on a garden hose. As a result, the bladder wall becomes thicker and irritable. The bladder begins to contract even when it contains small amounts of urine, causing more frequent urination. Eventually, the bladder weakens and loses the ability to empty itself, so urine remains in the bladder.

Infection

Infections cause swelling and irritation, or inflammation. A urinary tract infection (UTI) may cause retention if the urethra becomes inflamed and swells shut.

Surgery

During surgery, anesthesia is often administered to block pain signals, and fluid is given intravenously to compensate for possible blood loss. The combination may result in a full bladder with impaired nerve function. Consequently, many patients have urinary retention after surgery.

Medication

Many medicines work by calming overactive nerve signals. Various classes of drugs that block various signals may be used to treat allergies, stomach cramps, muscle spasms, anxiety, or depression. Some medicines are used to treat urinary incontinence and overactive bladder. The drugs that may cause urinary retention include

 antihistamines to treat allergies
 fexofenadine (Allegra)
 diphenhydramine (Benadryl)
 chlorpheniramine (Chlor-Trimeton)
 cetirizine (Zyrtec)
 anticholinergics/antispasmodics to treat stomach cramps, muscle spasms, and urinary incontinence
 hyoscyamine (Levbid, Cystospaz, Anaspaz, Gastrosed)
 oxybutynin (Ditropan, Ditropan XL, Oxytrol)
 tolterodine (Detrol, Detrol LA)
 propantheline (Pro-Banthine)
 tricyclic antidepressants to treat anxiety and depression
 imipramine (Tofranil)
 amitriptyline (Elavil, Endep)
 nortriptyline (Aventyl, Pamelor)
 doxepin (Novo-Doxepin, Sinequan)
(Source: National Kidney and Urologic Diseases Information Clearinghouse, October 2007)

Bladder Stone

A stone formed anywhere in the urinary tract may become lodged in the bladder. If the stone is large enough, it can block the opening to the urethra like a bathtub plug.

Cystocele and Rectocele

A cystocele occurs when the wall between a woman’s bladder and her vagina weakens and allows the bladder to droop into the vagina. The abnormal position of the bladder may cause urine to remain trapped. In a rectocele, the rectum droops into the back wall of the vagina.

Cystocele and rectocele are often the results of a dropping of the pelvic support floor for the bladder. This sagging can pull the bladder out of position and cause urinary problems such as incontinence or urinary retention.

Constipation

A hard stool in the rectum may push against the bladder and urethra, causing the urethra to be pinched shut, especially if a rectocele is present.

Urethral Stricture

A stricture is a narrowing or closure of a tube. Men may have a narrowing of the urethra, usually caused by scarring after a trauma to the penis. Infection is a less common cause of scarring and closure in the urethra.

Overview I I Signs and Symptoms

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Information Source: National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC) (October 2007). Urinary Retention (NIH Publication No. 08–6089). Web site: http://kidney.niddk.nih.gov/kudiseases/pubs/UrinaryRetention/index.htm. Retrieved June 2008.

Page Last Revised: July 2, 2010