sign in sign up
<<
Home , Anus, Bladder stone, Nerve, Rectocele, Rib, Toilet

Urinary Retention

National and Urologic Information Clearinghouse

What is ? What is the urinary tract Urinary retention is the inability to and how does it work? empty the bladder completely. Urinary The urinary tract is the body’s drainage retention can be acute or chronic. Acute system for removing , which is urinary retention happens suddenly and composed of and extra fluid. In lasts only a short time. People with acute order for normal to occur, all urinary retention cannot urinate at all, body parts in the urinary tract need to work even though they have a full bladder. together in the correct order. Acute urinary retention, a potentially life-threatening medical condition, Kidneys. The kidneys are two bean-shaped requires immediate emergency treatment. organs, each about the size of a fist. They Acute urinary retention can cause great are located just below the cage, one discomfort or . on each side of the spine. Every day, the kidneys filter about 120 to 150 quarts of Chronic urinary retention can be a long- to produce about 1 to 2 quarts of lasting medical condition. People with urine. The kidneys work around the clock; chronic urinary retention can urinate. a person does not control what they do. However, they do not completely empty all of the urine from their bladders. . Ureters are the thin tubes of Often people are not even aware they muscle—one on each side of the bladder— have this condition until they develop that carry urine from each of the kidneys to another problem, such as urinary the bladder. incontinence—loss of bladder control, Bladder. The bladder, located in the resulting in the accidental loss of urine— between the pelvic , is a hollow, or a urinary tract (UTI), muscular, balloon-shaped that an illness caused by harmful expands as it fills with urine. Although a growing in the urinary tract. person does not control kidney function, a person does control when the bladder empties. Bladder emptying is known as urination. The bladder stores urine until the person finds an appropriate time and place to urinate. A normal bladder acts like a reservoir and can hold 1.5 to 2 cups bladder is the bladder . The bladder of urine. How often a person needs to neck, composed of the second set of urinate depends on how quickly the kidneys muscles known as the internal sphincter, produce the urine that fills the bladder. helps urine stay in the bladder. The third The muscles of the bladder wall remain set of muscles is the muscles, relaxed while the bladder fills with urine. also referred to as the external sphincter, As the bladder fills to capacity, signals which surround and support the . sent to the tell a person to find a To urinate, the brain signals the muscular soon. During urination, the bladder bladder wall to tighten, squeezing urine empties through the urethra, located at the out of the bladder. At the same time, bottom of the bladder. the brain signals the sphincters to relax. Three sets of muscles work together like a As the sphincters relax, urine exits the dam, keeping urine in the bladder. bladder through the urethra. The first set is the muscles of the urethra itself. The area where the urethra joins the

Kidney

Ureter

Bladder

Prostate

Urethra

Male and female urinary tracts

2 Urinary Retention What causes urinary phase of growth begins around age 25 and continues during most of a man’s life. retention? Benign prostatic hyperplasia often occurs Urinary retention can result from with the second phase of growth. • obstruction of the urethra As the enlarges, the presses • problems against and pinches the urethra. The bladder wall becomes thicker. Eventually, • the bladder may weaken and lose the ability • weakened bladder muscles to empty completely, leaving some urine in the bladder. Obstruction of the Urethra Read more in Prostate Enlargement: Obstruction of the urethra causes urinary Benign Prostatic Hyperplasia at retention by blocking the normal urine www.urologic.niddk.nih.gov. flow out of the body. Conditions such as benign prostatic hyperplasia—also called . A urethral stricture BPH—urethral stricture, urinary tract is a narrowing or closure of the urethra. stones, , rectocele, , Causes of urethral stricture include and certain tumors and can cause and tissue from , an obstruction. , recurring UTIs, or . In men, a urethral stricture may result from Benign prostatic hyperplasia. For men , scarring after an injury to the in their 50s and 60s, urinary retention is or , or surgery for benign often caused by prostate enlargement due prostatic hyperplasia and prostate . to benign prostatic hyperplasia. Benign Prostatitis is a frequently painful condition prostatic hyperplasia is a medical condition that involves inflammation of the prostate in which the prostate gland is enlarged and and sometimes the areas around the not cancerous. The prostate is a walnut- prostate. The perineum is the area between shaped gland that is part of the male the and the organs. Since men . The gland surrounds have a longer urethra than women, urethral the urethra at the neck of the bladder. stricture is more common in men than The bladder neck is the area where the women.1 urethra joins the bladder. The prostate goes through two main periods of growth. Read more in Prostatitis: Inflammation of The first occurs early in puberty, when the Prostate at www.urologic.niddk.nih.gov. the prostate doubles in size. The second

1Urethral stricture. Mayo Clinic website. www.mayoclinic.org/urethral-stricture/about.html. Updated November 20, 2012. Accessed April 1, 2014. 3 Urinary Retention Surgery to correct pelvic organ , Rectocele. A rectocele is a bulging of the such as cystocele and rectocele, and urinary into the . A rectocele occurs incontinence can also cause urethral when the muscles and supportive tissues stricture. The urethral stricture often gets between a ’s rectum and vagina better a few weeks after surgery. weaken and stretch, letting the rectum sag from its normal position and bulge into Urethral stricture and acute or chronic the vagina. The abnormal position of the urinary retention may occur when the rectum may cause it to press against and muscles surrounding the urethra do not pinch the urethra. relax. This condition happens mostly in women. Constipation. Constipation is a condition in which a person has fewer than three Urinary tract stones. Urinary tract stones bowel movements a week or has bowel develop from crystals that form in the urine movements with stools that are hard, dry, and build up on the inner surfaces of the and small, making them painful or difficult kidneys, ureters, or bladder. The stones to pass. A person with constipation may formed or lodged in the bladder may block feel bloated or have pain in the — the opening to the urethra. the area between the chest and . Some Cystocele. A cystocele is a bulging of the people with constipation often have to bladder into the vagina. A cystocele occurs strain to have a bowel movement. Hard when the muscles and supportive tissues stools in the rectum may push against the between a woman’s bladder and vagina bladder and urethra, causing the urethra weaken and stretch, letting the bladder sag to be pinched, especially if a rectocele is from its normal position and bulge into present. the vagina. The abnormal position of the Read more in Constipation at bladder may cause it to press against and www.digestive.niddk.nih.gov. pinch the urethra. Tumors and cancers. Tumors and Read more in Cystocele at cancerous tissues in the bladder or urethra www.urologic.niddk.nih.gov. can gradually expand and obstruct urine flow by pressing against and pinching the urethra or by blocking the bladder outlet. Tumors may be cancerous or noncancerous.

4 Urinary Retention Nerve Problems Many patients have urinary retention right Urinary retention can result from problems after surgery. During surgery, with the that control the bladder is often used to block pain signals in the and sphincters. Many events or conditions nerves, and fluid is given intravenously to can interfere with nerve signals between compensate for possible blood loss. The the brain and the bladder and sphincters. combination of anesthesia and intravenous If the nerves are damaged, the brain may (IV) fluid may result in a full bladder with not get the signal that the bladder is full. impaired nerve function, causing urinary Even when a person has a full bladder, the retention. Normal bladder nerve function bladder muscles that squeeze urine out may usually returns once anesthesia wears off. not get the signal to push, or the sphincters The patient will then be able to empty the may not get the signal to relax. People bladder completely. of all ages can have nerve problems that Medications interfere with bladder function. Some of the most common causes of nerve problems Various classes of medications can cause include urinary retention by interfering with nerve signals to the bladder and prostate. These • vaginal medications include • brain or or • to treat −− cetirizine (Zyrtec) • −− chlorpheniramine (Chlor-Trimeton) • −− (Benadryl) • −− fexofenadine (Allegra) • pelvic injury or trauma • /antispasmodics to • heavy metal poisoning treat , muscle spasms, In addition, some children are born with and defects that affect the coordination of nerve −− hyoscyamine (Levbid) signals among the bladder, spinal cord, and brain. and other birth defects −− (Ditropan) that affect the spinal cord can to −− propantheline (Pro-Banthine) urinary retention in newborns. −− (Detrol) Read more in Nerve Disease and Bladder Control and Urine Blockage in Newborns at www.urologic.niddk.nih.gov.

5 Urinary Retention • tricyclic antidepressants to treat Over-the-counter cold and and medications that contain , such as , and −− (Elavil) antihistamines, such as diphenhydramine, −− (Adapin) can increase symptoms of urinary retention −− (Tofranil) in men with prostate enlargement. −− (Pamelor) Weakened Bladder Muscles Other medications associated with urinary Aging is a common cause of weakened retention include bladder muscles. Weakened bladder muscles may not contract strongly enough • decongestants or long enough to empty the bladder −− completely, resulting in urinary retention. −− phenylephrine How common is urinary −− pseudoephedrine retention? • nifedipine (Procardia), a Urinary retention in men becomes more to treat high and chest common with age. pain • In men 40 to 83 years old, the overall • carbamazepine (Tegretol), a incidence of urinary retention is 4.5 to medication to control in 6.8 per 1,000 men.2 people with epilepsy • For men in their 70s, the overall • (Flexeril), a muscle incidence increases to 100 per relaxant medication 1,000 men.2 • (Valium), a medication used • For men in their 80s, the incidence to relieve anxiety, muscle spasms, and of acute urinary retention is 300 per seizures 1,000 men.2 • nonsteroidal anti-inflammatory drugs • •

2Selius BA, Subedi R. Urinary retention in adults: diagnosis and initial management. American Family Physician. 2008;77(5):643–650. 6 Urinary Retention Urinary retention in women is less • feeling the need to urinate after common, though not rare.3 The incidence finishing urination of urinary retention in women has not • mild and constant discomfort in the been studied because researchers have lower abdomen and urinary tract primarily thought of urinary retention as a man’s problem related to the prostate.4 Some people with chronic urinary retention may not have symptoms that lead them to seek medical care. People who are unaware What are the symptoms they have chronic urinary retention of urinary retention? may have a higher chance of developing The symptoms of acute urinary retention complications. may include the following and require immediate medical attention: • inability to urinate When to Seek Medical • painful, urgent need to urinate Care • pain or discomfort in the lower A person who has any of the following abdomen symptoms should see a health care • bloating of the lower abdomen provider right away: The symptoms of chronic urinary retention • complete inability to urinate may include • great discomfort or pain in the • urinary frequency—urination eight or lower abdomen and urinary tract more times a day • trouble beginning a urine stream • a weak or an interrupted urine stream • an urgent need to urinate with little success when trying to urinate

3Wein AJ, Kavoussi LR, Novick AC, et al. Campbell- Walsh . 10th ed. Philadelphia: Saunders; 2011. 4Mevcha A, Drake MJ. Etiology and management of urinary retention in women. Indian Journal of Urology. 2010;26(2):230–235. 7 Urinary Retention How is urinary retention provider’s office, a center, or a hospital, and a radiologist—a doctor who diagnosed? specializes in —interprets A health care provider diagnoses acute or the images. The patient does not need chronic urinary retention with anesthesia. • a physical exam A health care provider may use a • postvoid residual measurement —a thin, flexible tube—to measure postvoid residual. The health care provider A health care provider may use the inserts the catheter through the urethra following medical tests to help determine into the bladder, a procedure called the cause of urinary retention: catheterization, to drain and measure the • amount of remaining urine. A postvoid residual of 100 mL or more indicates the • computerized tomography (CT) scans bladder does not empty completely. A • urodynamic tests health care provider performs this test during an office visit. The patient often • receives local anesthesia. Physical Exam Medical Tests A health care provider may suspect urinary retention because of a patient’s symptoms Cystoscopy. Cystoscopy is a procedure that and, therefore, perform a physical exam requires a tubelike instrument, called a of the lower abdomen. The health care cystoscope, to look inside the urethra and provider may be able to feel a distended bladder. A health care provider performs bladder by lightly tapping on the lower belly. cystoscopy during an office visit or in an outpatient center or a hospital. The patient Postvoid Residual Measurement will receive local anesthesia. However, in some cases, the patient may receive This test measures the amount of urine sedation and regional or general anesthesia. left in the bladder after urination. The A health care provider may use cystoscopy remaining urine is called the postvoid to diagnose urethral stricture or look for a residual. A specially trained technician blocking the opening of the performs an , which uses urethra. harmless sound waves to create a picture of the bladder, to measure the postvoid Read more in Cystoscopy and residual. The technician performs the at www.urologic.niddk.nih.gov. bladder ultrasound in a health care

8 Urinary Retention CT scans. CT scans use a combination of provider will perform these tests during an x rays and computer to create office visit. For tests that use a catheter, the images. For a CT scan, a health care patient often receives local anesthesia. provider may give the patient a solution • Uroflowmetry. Uroflowmetry to drink and an injection of a special dye, measures urine speed and volume. called contrast medium. CT scans require Special equipment automatically the patient to lie on a table that slides into measures the amount of urine and the a tunnel-shaped device where a technician flow rate—how fast urine comes out. takes the x rays. An x-ray technician Uroflowmetry equipment includes performs the procedure in an outpatient a device for catching and measuring center or a hospital, and a radiologist urine and a computer to record the interprets the images. The patient does not data. The equipment creates a graph need anesthesia. A health care provider that shows changes in flow rate from may give infants and children a sedative to second to second so the health care help them fall asleep for the test. CT scans provider can see the highest flow can show rate and how many seconds it takes • urinary tract stones to get there. A weak bladder muscle or blocked urine flow will yield an • UTIs abnormal test result. • tumors • Pressure flow study. A pressure flow • traumatic injuries study measures the bladder pressure • abnormal, fluid-containing sacs called required to urinate and the flow rate cysts a given pressure generates. A health care provider places a catheter with Urodynamic tests. Urodynamic tests a manometer into the bladder. The include a variety of procedures that look manometer measures bladder pressure at how well the bladder and urethra store and flow rate as the bladder empties. and release urine. A health care provider A pressure flow study helps diagnose may use one or more urodynamic tests to bladder outlet obstruction. diagnose urinary retention. The health care

9 Urinary Retention • Video urodynamics. This test uses How is urinary retention x rays or ultrasound to create real-time images of the bladder and urethra treated? during the filling or emptying of the A health care provider treats . For x rays, a health care retention with provider passes a catheter through • bladder drainage the urethra into the bladder. He or she fills the bladder with contrast • urethral dilation medium, which is visible on the video • urethral images. Video urodynamic images can show the size and shape of the urinary • prostate medications tract, the flow of urine, and causes of • surgery urinary retention, such as bladder neck The type and length of treatment depend obstruction. on the type and cause of urinary retention. Read more in at www.urologic.niddk.nih.gov. Bladder Drainage Bladder drainage involves catheterization Electromyography. Electromyography uses to drain urine. Treatment of acute urinary special sensors to measure the electrical retention begins with catheterization activity of the muscles and nerves in and to relieve the immediate distress of around the bladder and sphincters. A a full bladder and prevent bladder specially trained technician places sensors damage. A health care provider performs on the near the urethra and rectum catheterization during an office visit or in or on a urethral or rectal catheter. The an outpatient center or a hospital. The sensors record, on a , muscle and patient often receives local anesthesia. The nerve activity. The patterns of the nerve health care provider can pass a catheter impulses show whether the messages through the urethra into the bladder. In sent to the bladder and sphincters cases of a blocked urethra, he or she can coordinate correctly. A technician pass a catheter directly through the lower performs electromyography in a health abdomen, just above the pubic , care provider’s office, an outpatient center, directly into the bladder. In these cases, the or a hospital. The patient does not need health care provider will use anesthesia. anesthesia if the technician uses sensors placed on the skin. The patient will receive local anesthesia if the technician uses sensors placed on a urethral or rectal catheter.

10 Urinary Retention For chronic urinary retention, the patient Prostate Medications may require intermittent—occasional, Medications that stop the growth of or or not continuous—or long-term shrink the prostate or relieve if other treatments do retention symptoms associated with benign not work. Patients who need to continue prostatic hyperplasia include intermittent catheterization will receive instruction regarding how to self- • (Avodart) catheterize to drain urine as necessary. • (Proscar) Urethral Dilation The following medications relax the Urethral dilation treats urethral stricture muscles of the bladder outlet and prostate by inserting increasingly wider tubes into to help relieve blockage: the urethra to widen the stricture. An • alfuzosin (Uroxatral) alternative dilation method involves inflating a small balloon at the end of a • doxazosin (Cardura) catheter inside the urethra. A health care • (Rapaflo) provider performs a urethral dilation during an office visit or in an outpatient center or • tadalafil (Cialis) a hospital. The patient will receive local • (Flomax) anesthesia. In some cases, the patient will • (Hytrin) receive sedation and regional anesthesia. Surgery Urethral Stents Prostate surgery. To treat urinary retention Another treatment for urethral stricture caused by benign prostatic hyperplasia, a involves inserting an artificial tube, called urologist—a doctor who specializes in the a , into the urethra to the area of urinary tract—may surgically destroy or the stricture. Once in place, the stent remove enlarged prostate tissue by using expands like a spring and pushes the the transurethral method. For transurethral surrounding tissue, widening the urethra. surgery, the urologist inserts a catheter or Stents may be temporary or permanent. surgical instruments through the urethra A health care provider performs stent to reach the prostate. Removal of the placement during an office visit or in an enlarged tissue usually relieves the blockage outpatient center or a hospital. The patient and urinary retention caused by benign will receive local anesthesia. In some prostatic hyperplasia. A urologist performs cases, the patient will receive sedation and some procedures on an outpatient basis. regional anesthesia. Some men may require a hospital stay. In

11 Urinary Retention some cases, the urologist will remove the other pelvic organs. The urologist places entire prostate using open surgery. Men stitches in the tissue to close up the defect will receive general anesthesia and have a and then closes the incision in the vaginal longer hospital stay than for other surgical wall with more stitches, removing any extra procedures. Men will also have a longer tissue. These stitches tighten the layers of rehabilitation period for open surgery. tissue that separate the organs, creating more support for the pelvic organs. A Read more in Prostate Enlargement: urologist or gynecologist––a doctor who Benign Prostatic Hyperplasia at specializes in the female reproductive www.urologic.niddk.nih.gov. system––performs the surgery to repair Internal . A urologist can a cystocele or rectocele in a hospital. repair a urethral stricture by performing an Women will receive anesthesia. internal urethrotomy. For this procedure, Tumor and cancer surgery. Removal of the urologist inserts a special catheter into tumors and cancerous tissues in the bladder the urethra until it reaches the stricture. or urethra may reduce urethral obstruction The urologist then uses a knife or laser to and urinary retention. make an incision that opens the stricture. The urologist performs an internal urethrotomy in an outpatient center or a What are the complications hospital. The patient will receive general of urinary retention and its anesthesia. treatments? Cystocele or rectocele repair. Women Complications of urinary retention and its may need surgery to lift a fallen bladder treatments may include or rectum into its normal position. The most common procedure for cystocele and • UTIs rectocele repair involves a urologist, who • bladder damage also specializes in the female reproductive • kidney damage system, making an incision in the wall of the vagina. Through the incision, the urologist • urinary incontinence after prostate, looks for a defect or hole in the tissue that tumor, or cancer surgery normally separates the vagina from the

12 Urinary Retention UTIs. Urine is normally sterile, and the How can urinary retention normal flow of urine usually prevents bacteria from infecting the urinary tract. be prevented? With urinary retention, the abnormal urine People can prevent urinary retention before flow gives bacteria at the opening of the it occurs by treating some of the potential urethra a chance to infect the urinary tract. causes. For example, men with benign prostatic hyperplasia should take prostate Bladder damage. If the bladder becomes medications as prescribed by their health stretched too far or for long periods, the care provider. Men with benign prostatic muscles may be permanently damaged and hyperplasia should avoid medications lose their ability to contract. associated with urinary retention, such Kidney damage. In some people, urinary as over-the-counter cold and allergy retention causes urine to flow backward medications that contain decongestants. into the kidneys. This backward flow, called Women with mild cystocele or rectocele reflux, may damage or scar the kidneys. may prevent urinary retention by doing exercises to strengthen the pelvic muscles. Urinary incontinence after prostate, tumor, In most cases, dietary and lifestyle changes or cancer surgery. Transurethral surgery will help prevent urinary retention caused to treat benign prostatic hyperplasia may by constipation. People whose constipation result in urinary incontinence in some men. continues should see a health care provider. This problem is often temporary. Most men recover their bladder control in a few Read more about exercises to strengthen weeks or months after surgery. Surgery to the pelvic muscles in Tips at remove tumors or cancerous tissue in the www.urologic.niddk.nih.gov. bladder, prostate, or urethra may also result in urinary incontinence. , Diet, and Nutrition Researchers have not found that eating, diet, and nutrition play a role in causing or preventing urinary retention.

13 Urinary Retention Points to Remember • A health care provider diagnoses acute or chronic urinary retention • Urinary retention is the inability to with empty the bladder completely. −− a physical exam • Urinary retention can be acute or chronic. −− postvoid residual measurement • Urinary retention can result from • A health care provider may use the following medical tests to help −− obstruction of the urethra determine the cause of urinary −− nerve problems retention: −− medications −− cystoscopy −− weakened bladder muscles −− computerized tomography (CT) • The symptoms of acute urinary scans retention may include the following −− urodynamic tests and require immediate medical −− electromyography attention: • A health care provider treats urinary −− inability to urinate retention with −− painful, urgent need to urinate −− bladder drainage −− pain or discomfort in the lower −− urethral dilation abdomen −− urethral stents −− bloating of the lower abdomen −− prostate medications • The symptoms of chronic urinary retention may include −− surgery −− urinary frequency—urination eight • Complications of urinary retention or more times a day and its treatments may include −− trouble beginning a urine stream −− urinary tract infections (UTIs) −− a weak or an interrupted urine −− bladder damage stream −− kidney damage −− an urgent need to urinate with −− urinary incontinence after little success when trying to urinate prostate, tumor, or cancer surgery −− feeling the need to urinate after • People can prevent urinary retention finishing urination before it occurs by treating some of −− mild and constant discomfort in the potential causes. the lower abdomen and urinary tract

14 Urinary Retention Hope through Research Society of Urologic Nurses and Associates East Holly Avenue, Box 56 The National Institute of Diabetes and Pitman, NJ 08071–0056 Digestive and Kidney Diseases (NIDDK) Phone: 1–888–TAP–SUNA conducts and supports research into many (1–800–827–7862) kinds of urinary tract disorders, including Email: [email protected] urinary retention. The knowledge gained Internet: www.suna.org from these studies is advancing scientific understanding of why urinary tract disorders Urology Care Foundation develop, leading to improved methods of 1000 Corporate Boulevard diagnosing, treating, and preventing them. Linthicum, MD 21090 Phone: 1–800–828–7866 or 410–689–3700 Clinical trials are research studies involving Fax: 410–689–3998 people. Clinical trials look at safe and Email: [email protected] effective new ways to prevent, detect, or Internet: www.UrologyHealth.org treat disease. Researchers also use clinical trials to look at other aspects of care, such For information about bladder, prostate, as improving the quality of life for people and , contact the with chronic illnesses. To learn more about National Cancer Institute clinical trials, why they matter, and how to BG 9609 MCS 9760 participate, visit the NIH Clinical Research 9609 Medical Center Drive Trials and You website at www.nih.gov/ Bethesda, MD 20892 health/clinicaltrials. For information about Phone: 1–800–4–CANCER current studies, visit www.ClinicalTrials.gov. (1–800–422–6237) Internet: www.cancer.gov For More Information American Prostate Society Acknowledgments 10 East Lee Street, Suite 1504 Publications produced by the Baltimore, MD 21202 Clearinghouse are carefully reviewed by Phone: 1–877–850–3735 or 410–837–3735 both NIDDK scientists and outside experts. (Tuesday and Friday only) This publication was originally reviewed by Fax: 410–837–8510 J. Curtis Nickel, M.D., Queen’s University Email: [email protected] at Kingston, Ontario. Anthony J. Schaeffer, Internet: www.americanprostatesociety.com M.D., Northwestern University, reviewed the updated version of this publication.

15 Urinary Retention You may also find additional information about this National Kidney topic by visiting MedlinePlus at www..gov. and Urologic Diseases This publication may contain information about medications and, when taken as prescribed, Information Clearinghouse the conditions they treat. When prepared, this publication included the most current information 3 Information Way available. For updates or for questions about Bethesda, MD 20892–3580 any medications, contact the U.S. Food and Drug Administration toll-free at 1–888–INFO–FDA Phone: 1–800–891–5390 (1–888–463–6332) or visit www.fda.gov. Consult your TTY: 1–866–569–1162 health care provider for more information. Fax: 703–738–4929 Email: [email protected] Internet: www.urologic.niddk.nih.gov The U.S. Government does not endorse or favor any The National Kidney and Urologic Diseases specific commercial product or company. rade,T proprietary, or company names appearing in this Information Clearinghouse (NKUDIC) document are used only because they are considered is a service of the National Institute necessary in the context of the information provided. of Diabetes and Digestive and Kidney If a product is not mentioned, the omission does not mean or imply that the product is unsatisfactory. Diseases (NIDDK). The NIDDK is part of the National Institutes of Health of the U.S. Department of Health and Services. Established in 1987, the Clearinghouse provides information about diseases of the kidneys and urologic system to people with kidney and urologic disorders and to their families, health care professionals, and the public. The NKUDIC answers inquiries, develops and distributes publications, and works closely with professional and patient organizations and Government agencies to coordinate resources about kidney and urologic diseases.

This publication is not copyrighted. The Clearinghouse encourages users of this publication to duplicate and distribute as many copies as desired. This publication is available at www.urologic.niddk.nih.gov.

NIH Publication No. 14–6089 July 2014

The NIDDK prints on recycled paper with bio-based ink.