What Causes Urinary Retention?

There are a number of conditions that can keep your bladder from emptying. Each typically falls under one of these four categories:

• Your urethra is blocked (the urethra is the thin muscular tube that carries urine from the bladder)
• Nerve problems
• Medications
• Weakened bladder muscles ^5,6,8,9

If your urethra is blocked or narrowed, urine can’t flow out of the body. Conditions that may cause this block include: 

Benign prostatic hyperplasia (BPH). BPH affects the prostate, which is typically a walnut-sized gland that surrounds the urethra. It is a condition in which the prostate is enlarged but not cancerous. When it is enlarged, it can compress the urethra, making it difficult to pass urine. Over time, the bladder wall becomes thicker. Eventually, the bladder may weaken and lose the ability to empty completely, leaving some urine in the bladder. This is a common cause of urinary retention for men in their 50s and 60s. ^2,5,6,9

Urethral stricture. This means there is a narrowing or closure of the urethra. Surgery, scar tissue from surgery, disease, recurring UTIs, or injury can cause it. Prostatitis, which is inflammation of the prostate, is a common cause of urethral stricture in men. And since men have a longer urethra than women, urethral stricture is more common in men than women. Urethral stricture and acute or chronic urinary retention may occur when the muscles surrounding the urethra do not relax. This condition happens mostly in women. ^5,6,7,9

Urinary tract stones. When crystals form in the urine, they can build up and form urinary tract stones. These crystals may build up on the inner surfaces of the kidneys, ureters, or bladder. Stones in your bladder may block the opening to the urethra and cause urinary retention. ^5,9

Cystocele. A cystocele is when the bladder pushes into the vagina. This happens because the muscles and supportive tissues between a woman’s bladder and her vagina weaken and stretch. This allows the bladder to sag from its normal position and bulge into the vagina. It may also press against and pinch the urethra. ^5,9

Rectocele. A rectocele is when the rectum pushes into the vagina. Like cystocele, this happens when the muscles and supportive tissues between a woman’s rectum and vagina weaken and stretch. The rectum sags from its normal position and bulges into the vagina and may press against and pinch the urethra. ^5,9

Constipation. A hard stool in the rectum can cause urinary retention by pressing against the bladder and urethra. A rectocele makes this more likely to happen. ^5,9

Tumors and cancers. A cancerous or noncancerous tumor in the bladder or urethra can gradually grow larger. Over time it may block the bladder outlet or press against and pinch the urethra. Either of these can block urine flow. ^5,9

The second category of conditions that can cause urinary retention are nerve problems.

Nerves pass signals between the brain and the bladder and the sphincters. Both the bladder and sphincters (small ring-like muscles) tighten or relax to control the flow of urine. There are a number of events or conditions that can interfere with these signals. When this happens, the brain may not get the signal that the bladder is full. Or the bladder muscles that squeeze urine out may not get the signal to push. Or the sphincters may not get the signal to relax and allow the urine to flow out. ^{1, 5,8,9}

Nerve problems like this can happen to you no matter how young you are. For example, a baby may be born with spina bifida, which affects the spinal cord and can cause urinary retention. ^1,5,6

The most common causes of nerve problems that can lead to temporary or permanent urinary retention are:

• Vaginal childbirth
• Brain or spinal cord infections or injuries
• Diabetes
• Stroke
• Multiple sclerosis
• Pelvic injury or trauma^1,5,6,9

Urinary retention can also be caused by medications that interfere with nerve signals to the bladder and prostate. 

• Antihistamines to treat allergies
• Anticholinergics/antispasmodics to treat stomach cramps, muscle spasms, and urinary incontinence
• Tricyclic antidepressants to treat anxiety and depression ^5,9

If you are a man with prostate enlargement, some over-the-counter cold and allergy medications can increase your symptoms of urinary retention. This is true of the ones that contain decongestants, like pseudoephedrine, and antihistamines, such as diphenhydramine. ⁵

Finally, weakened bladder muscles can also cause urinary retention.

As you age, many of your muscles may weaken, including the bladder and the muscles around it. They may not contract strongly enough or long enough to empty the bladder completely, resulting in urinary retention. ^5,6,9

Please note that this information provided by BARD Medical is not intended to be used in place of a visit, consultation, or advice of a medical professional. Information is as of 12/2014.  Please check references for updated information. 

References

1. Urology Care Foundation – Neurogenic Bladder Symptoms, Updated May 2014 http://www.urologyhealth.org/urology/index.cfm?article=9#SymptomNB
2. Kirby R.S. Prostate Disease and their Treatments, Health Press Oxford 2010
3. Diseases and Conditions; Benign Prostatic Hyperplasia (BPH), Updated 12/2001 http://www.mayoclinic.org/diseases-conditions/benign-prostatic-hyperplasia/basics/symptoms/con-20030812
4. Lepo H, Managing and Preventing Acute Urinary Retention, Urol. 2005; 7 (Suppl 8) S26-S33
5. National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC) Urinary Retention Updated 8/2014 http://kidney.niddk.nih.gov/KUDiseases/pubs/UrinaryRetention/UrinaryRetention_508.pdf
6. R Appell MD, Voiding Dysfunction – Diagnosis and Treatment, Humana Press Inc. New Jersey 2000
7. A Wein MD, Campbell-Walsh Urology, Elsevier Saunders, Philadelphia PA, 2012
8. A Slack, D Newman, A Wein MD, Fast Facts: Bladder Disorders, Oxford Press Ltd., Oxford UK, 2011
9. B Selius DO, R Subedi MD, Urinary Retention in Adults: Diagnosis and Management, American Family Physician, Volume 77 Number 3, 2008