What I need to know about

Urinary Tract Infections

National Kidney and Urologic Diseases

Information Clearinghouse

What I need to know about 

Urinary Tract Infections
Contents 

What is a urinary tract infection (UTI)?............... 1

What is the urinary tract?....................................... 1

What causes UTIs? ................................................. 3

Who gets UTIs?....................................................... 3

Are UTIs serious?................................................... 5

What are the signs and symptoms 

of a UTI?.................................................................. 5

How are UTIs diagnosed?...................................... 6

How are UTIs treated?......................................... 12

Will UTIs come back? .......................................... 13

How can I prevent repeat UTIs? ......................... 14

Points to Remember ............................................. 15

Hope through Research........................................ 18

Pronunciation Guide............................................. 19

For More Information .......................................... 20

Acknowledgments ................................................. 21
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

What is a urinary tract infection (UTI)? 

A UTI is an infection in the urinary tract. 

Infections are caused by microbes—organisms too 

small to be seen without a microscope. Bacteria* 

are the most common cause of UTIs. Normally, 

bacteria that enter the urinary tract are quickly 

removed by the body before they cause symptoms. 

But sometimes bacteria overcome the body’s 

natural defenses and cause infection. 

What is the urinary tract? 

The urinary tract is the body’s drainage system 

for removing wastes and extra water. The urinary 

tract includes two kidneys, two ureters, a bladder, 

and a urethra. The kidneys are a pair of beanshaped organs, each about the size of a fist. They 

are located below the ribs, one on each side of 

the spine, toward the middle of the back. Every 

minute, your kidneys filter about 3 ounces of 

blood, removing wastes and extra water. The 

wastes and extra water make up the 1 to 2 quarts 

*See page 19 for tips on how to say the words in 

bold type. 

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of urine you produce each day. The urine travels 

from the kidneys down two narrow tubes called the 

ureters. The urine is then stored in a balloonlike 

organ called the bladder and emptied through the 

urethra, a tube at the bottom of the bladder. 

Kidney 

Ureter 

Urethra 

Bladder 

Prostate 

Male and female urinary tracts 

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What causes UTIs? 

Most UTIs are caused by bacteria that live in the 

bowel. The bacterium Escherichia coli (E. coli) 

causes most UTIs. The urinary tract has several 

systems to prevent infection. The points where 

the ureters attach to the bladder act like one-way 

valves to prevent urine from backing up toward 

the kidneys, and urination washes microbes out 

of the body. In men, the prostate gland produces 

secretions that slow bacterial growth. In both 

sexes, immune defenses also prevent infection. But 

despite these safeguards, infections still occur. 

Who gets UTIs? 

People of any age or sex can get UTIs. But about 

four times as many women get UTIs as men. 

Women have a shorter urethra, which makes it 

easier for bacteria to reach the bladder. Also, the 

opening of a woman’s urethra is near the vagina 

and anus, where bacteria live. Women who use a 

diaphragm are also more likely to get UTIs than 

women who use other forms of birth control. 

3 
Others at higher risk for UTIs are people 

●	 with diabetes or problems with the body’s 

natural defense system 

●	 who need a tube to drain their bladder 

●	 with urinary tract abnormalities that block the 

flow of urine 

●	 with spinal cord injuries or other nerve damage 

About four times as many women get UTIs as men. 

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Are UTIs serious? 

Most UTIs are not serious, but some infections 

can lead to serious problems. Chronic kidney 

infections—infections that recur or last a long 

time—can cause permanent damage, including 

kidney scars, poor kidney function, high blood 

pressure, and other problems. Some acute kidney 

infections—infections that develop suddenly—can 

be life threatening, especially if the bacteria enter 

the bloodstream, a condition called septicemia. 

What are the signs and symptoms 

of a UTI? 

You should see your health care provider if you 

have any of these signs or symptoms: 

●	 a burning feeling when you urinate 

●	 frequent or intense urges to urinate, even when 

you have little urine to pass 

●	 pain in your back or side below the ribs 

●	 cloudy, dark, bloody, or foul-smelling urine 

●	 fever or chills 

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How are UTIs diagnosed? 

Health care providers diagnose UTIs by asking 

about your symptoms and then testing a sample 

of your urine. Your urine will be checked with 

a microscope for bacteria and white blood cells, 

which the body produces to fight infection. 

Because bacteria can be found in the urine of 

healthy people, a UTI is diagnosed based both on 

symptoms and a lab test. 

Your urine will be checked with a 

microscope for bacteria and white 

blood cells. 

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If you have repeat infections or are in the hospital, 

your urine may be cultured. The culture is 

performed by placing part of the urine sample in a 

tube or dish with a substance that encourages any 

bacteria present to grow. Once the bacteria have 

multiplied, which usually takes 1 to 3 days, they 

can be identified. Your health care provider may 

also order a sensitivity test, which tests the bacteria 

for sensitivity to different antibiotics to see which 

medicine is best for treating the infection. 

If you have repeat infections, your health care 

provider may also order one or more tests to see if 

your urinary tract is normal. 

Kidney and bladder ultrasound. Ultrasound uses 

a device, called a transducer, that bounces safe, 

painless sound waves off organs to create an image 

of their structure. The procedure is performed in a 

health care provider’s office, outpatient center, or 

hospital by a specially trained technician, and the 

images are interpreted by a radiologist—a doctor 

who specializes in medical imaging; anesthesia is 

not needed. The images can show abnormalities 

in the kidneys and bladder. However, this test 

cannot reveal all important urinary abnormalities 

or measure how well the kidneys work. 

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Voiding cystourethrogram. This test is an x-ray 

image of the bladder and urethra taken while the 

bladder is full and during urination, also called 

voiding. As you lie on the x-ray table, a health 

care provider inserts the tip of a thin, flexible tube 

called a catheter through your urethra into your 

bladder. Your bladder and urethra are filled with 

a special dye, called contrast medium, to make the 

structures clearly visible on the x-ray images. The 

x rays are taken from various angles while your 

bladder is full of contrast medium. The catheter 

is then removed and x-ray images are taken 

during urination. The procedure is performed in 

a health care provider’s office, outpatient center, 

or hospital by an x-ray technician. The technician 

is supervised by a radiologist while the images are 

taken. The radiologist then interprets the images. 

Anesthesia is not needed, but light sedation 

may be used if you need it. This test can show 

abnormalities of the inside of your urethra and 

bladder. The test can also determine whether the 

flow of urine is normal when your bladder empties. 

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Computerized tomography (CT) scan. CT 

scans use a combination of x rays and computer 

technology to create three-dimensional (3-D) 

images. A CT scan may include the injection of 

contrast medium. CT scans require you to lie on a 

table that slides into a tunnel-shaped device where 

the x rays are taken. The procedure is performed 

in an outpatient center or hospital by an x-ray 

technician, and the images are interpreted by a 

radiologist; anesthesia is not needed. CT scans can 

provide clearer, more detailed images to help the 

health care provider understand the problem. 

Magnetic resonance imaging (MRI). MRI 

machines use radio waves and magnets to produce 

detailed pictures of your body’s internal organs 

and soft tissues without using x rays. An MRI 

may include an injection of contrast medium. 

With most MRI machines, you lie on a table that 

slides into a tunnel-shaped device that may be 

open ended or closed at one end; some newer 

machines are designed to allow you to lie in a more 

open space. The procedure is performed in an 

outpatient center or hospital by a specially trained 

technician, and the images are interpreted by a 

radiologist; anesthesia is not needed though light 

sedation may be used if you have a fear of confined 

spaces. Like CT scans, MRIs can provide clearer, 

more detailed images. 

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Radionuclide scan. A radionuclide scan is an 

imaging technique that relies on the detection 

of small amounts of radiation after injection 

of radioactive chemicals. Because the dose of 

the radioactive chemicals is small, the risk of 

causing damage to cells is low. Special cameras 

and computers are used to create images of the 

radioactive chemicals as they pass through your 

kidneys. Radionuclide scans are performed in a 

health care provider’s office, outpatient center, or 

hospital by a specially trained technician, and the 

images are interpreted by a radiologist; anesthesia 

is not needed. Radioactive chemicals injected into 

your blood can provide information about your 

kidney function. Radioactive chemicals can also 

be put into the fluids used to fill your bladder and 

urethra for x ray, MRI, and CT imaging. 

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Urodynamics. Urodynamic testing is any 

procedure that looks at how well your bladder, 

sphincters, and urethra are storing and releasing 

urine. Most of these tests are performed in the 

office of a urologist—a doctor who specializes 

in urinary problems—by a urologist, physician 

assistant, or nurse practitioner. Some procedures 

may require light sedation to keep you calm. Most 

urodynamic tests focus on your bladder’s ability 

to hold urine and empty steadily and completely. 

Urodynamic tests can also show whether your 

bladder is having abnormal contractions that cause 

leakage. A health care provider may order these 

tests if there is evidence that you have some kind of 

nerve damage. 

Cystoscopy. Cystoscopy is a procedure that uses a 

tubelike instrument to look inside the urethra and 

bladder. Cystoscopy is performed by a doctor in a 

health care provider’s office, outpatient facility, or 

hospital with local anesthesia. However, in some 

cases, sedation and regional or general anesthesia 

are needed. Cystoscopy may be used to look for 

swelling, redness, and other signs of infection. 

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How are UTIs treated? 

UTIs are treated with antibiotics that can kill 

the bacteria causing the infection. The antibiotic 

prescribed will depend on the type of bacteria 

causing your UTI. Some antibiotics may be ruled 

out if you have allergies to them. Tell your health 

care provider if you are allergic to any medicines. 

You may need to take antibiotics for a few days 

or for 7 days or longer. The length of treatment 

depends on a few factors: 

●	 how severe the infection is 

●	 whether you were given the right antibiotic at first 

●	 whether the bacteria resists the antibiotic 

●	 whether you have repeat infections 

●	 whether you have a urinary tract abnormality 

that blocks the flow of urine 

●	 whether you are male or female; men may need 

longer treatment because bacteria can hide deep 

inside prostate tissue 

Follow your health care provider’s instructions 

carefully and completely when taking antibiotics. 

Drinking lots of fluids and urinating frequently will 

speed healing. If needed, you may take various 

medicines to relieve the pain of a UTI. A heating 

pad on the back or abdomen may also help. 

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Will UTIs come back? 

For most people, the answer is no. But about one 

out of every five young women who have a UTI 

will have another one. Some women have three or 

more UTIs a year. Men are less likely than women 

to have a first UTI. But once a man has a UTI, 

he is likely to have another because bacteria can 

hide deep inside prostate tissue. Anyone who has 

diabetes or a problem that makes it hard to urinate 

may have repeat infections. 

If you have repeat infections, your health care 

provider may refer you to a urologist. Talk with 

your health care provider or urologist about special 

treatment plans. For example, you may need to 

take antibiotics for a longer period of time to help 

prevent repeat infections. Some patients with 

frequent UTIs are given a supply of antibiotics to 

be started at the first sign of infection. Make sure 

you understand and follow the instructions your 

health care provider or urologist gives you. 

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How can I prevent repeat UTIs? 

In addition to taking antibiotics, changing some of 

your daily habits and lifestyle choices may help you 

prevent repeat UTIs. 

Eating, Diet, and Nutrition 

Drinking lots of fluid can help flush bacteria from 

your system. Water is best. Most people should 

try for six to eight, 8-ounce glasses a day. But do 

not drink this much fluid if you have kidney failure. 

Check with your health care provider to learn how 

much fluid is healthy for you. 

Bathroom Habits 

Urinate often and when you first feel the urge. 

Bacteria can grow when urine stays in the bladder 

too long. Urinate shortly after sex to flush away 

bacteria that might have entered your urethra 

during sex. Drinking a glass of water will also help 

flush bacteria away. 

After using the toilet, always wipe from front to 

back. This step is most important after a bowel 

movement to keep from getting bacteria into the 

urethra. 

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Clothing 

Wear cotton underwear and loose-fitting clothes 

so air can keep the area around the urethra dry. 

Avoid nylon underwear and tight-fitting jeans, 

which can trap moisture and help bacteria grow. 

Birth Control 

For women, using a diaphragm or spermicide 

for birth control can lead to UTIs by increasing 

bacteria growth. If you have trouble with UTIs, 

try switching to a new form of birth control. 

Unlubricated condoms or spermicidal condoms 

increase irritation, which may help bacteria grow. 

Consider switching to lubricated condoms without 

spermicide or using a nonspermicidal lubricant. 

Points to Remember 

●	 A urinary tract infection (UTI) is an infection 

in the urinary tract. Infections are caused by 

microbes—organisms too small to be seen 

without a microscope. 

●	 The urinary tract is the body’s drainage system 

for removing wastes and extra water. 

●	 Bacteria that live in the digestive tract, in the 

vagina, or around the urethra are the most 

common cause of UTIs. 

15 
●	 You should see your health care provider if you 

have any of these signs or symptoms: 

• a burning feeling when you urinate 

• frequent or intense urges to urinate, even 

when you have little urine to pass

• pain in your back or side below the ribs 

• cloudy, dark, bloody, or foul-smelling urine 

• fever or chills 

●	 Health care providers diagnose UTIs by asking 

about your symptoms and then testing a sample 

of your urine for bacteria. 

●	 If you have repeat infections or are in the 

hospital, your urine may be cultured. The 

culture is performed by placing part of the urine 

sample in a tube or dish with a substance that 

encourages any bacteria present to grow. 

●	 If you have repeat infections, your health care 

provider may also order one or more tests to see 

if your urinary tract is normal. 

• kidney and bladder ultrasound 

• voiding cystourethrogram 

• computerized tomography (CT) scan 

16 
• magnetic resonance imaging (MRI) 

• radionuclide scan 

• urodynamics 

• cystoscopy 

●	 UTIs are treated with antibiotics that can kill the 

bacteria causing the infection. The antibiotic 

prescribed will depend on the type of bacteria 

causing your UTI. 

●	 About one out of every five young women who 

have a UTI will have another one. Some women 

have three or more UTIs a year. 

●	 Men are less likely than women to have a first 

UTI. But once a man has a UTI, he is likely to 

have another because bacteria can hide deep 

inside prostate tissue. 

●	 Anyone who has diabetes or a problem that 

makes it hard to urinate may have repeat 

infections. 

●	 Changing some of your daily habits and lifestyle 

choices may help you prevent repeat UTIs. 

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Hope through Research 

Scientists supported by the National Institute 

of Diabetes and Digestive and Kidney Diseases 

(NIDDK) are working on ways to prevent UTIs 

using probiotics, good bacteria that help your 

body fight bad bacteria. One study is looking at a 

vaginal suppository of the probiotic Lactobacillus 

to replenish a woman’s natural supply of the 

protective bacteria. More information about 

the Intravaginal LACTIN-V for Prevention of 

Recurrent Urinary Tract Infection Trial, funded 

under National Institutes of Health clinical 

trial number NCT00305227, can be found at 

www.ClinicalTrials.gov. 

Participants in clinical trials can play a more 

active role in their own health care, gain access to 

new research treatments before they are widely 

available, and help others by contributing to 

medical research. For information about current 

studies, visit www.ClinicalTrials.gov. 

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Pronunciation Guide 

antibiotics (AN-tee-by-OT-ikss)

bacteria (bak-TIHR-ee-uh)

bladder (BLAD-ur)

computerized tomography (CT) scan (kom-PYOOtur-eyezd) (toh-MOG-ruh-fee) (scan)

cystoscopy (siss-TAHS-kuh-pee)

diaphragm (DY-uh-fram)

Escherichia coli (esh-uh-RIK-ee-uh) (KOH-ly)

kidneys (KID-neez)

prostate (PROSS-tayt)

spermicide (SPURM-ih-syd)

suppository (suh-POZ-ih-TOH-ree)

ultrasound (UHL-truh-sound)

ureters (YOOR-uh-turz)

urethra (yoo-REE-thruh)

urinary tract (YOOR-ih-NAIR-ee) (trakt)

urologist (yoo-ROL-uh-jist)

19 
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For More Information

The National Kidney and Urologic Diseases 

Information Clearinghouse (NKUDIC) has a fact 

sheet called Urinary Tract Infections in Adults that 

gives more information about UTIs and a fact 

sheet called Cystoscopy and Uteroscopy that gives 

more information about cystoscopy.

The following organizations also have fact sheets 

about UTIs.

American Urological Association Foundation 

1000 Corporate Boulevard 

Linthicum, MD 21090 

Phone: 1–800–828–7866 or 410–689–3700 

Fax: 410–689–3998 

Email: auafoundation@auafoundation.org 

Internet: www.UrologyHealth.org

National Kidney Foundation 

30 East 33rd Street 

New York, NY 10016 

Phone: 1–800–622–9010 or 212–889–2210 

Fax: 212–689–9261 

Internet: www.kidney.org
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Acknowledgments 

Publications produced by the Clearinghouse are 

carefully reviewed by both NIDDK scientists and 

outside experts. The NKUDIC would like to 

thank the following individuals for assisting with 

the scientific and editorial review of the original 

version of this publication: 

Anthony J. Schaeffer, M.D.

Chair, Department of Urology

Northwestern University Medical School

Betsy Foxman, Ph.D.

Associate Professor

Department of Epidemiology

School of Public Health

University of Michigan

Elaine Tracy, R.N.

Baylor College of Medicine

Thank you also to the Bread for the City free clinic 

in Washington, D.C., for facilitating field-testing of 

the original version of this publication. 

21 

 

 

 

 

3 Information Way 

National Kidney and Urologic 

Diseases Information Clearinghouse 

Bethesda, MD 20892–3580 

Phone: 1–800–891–5390 

TTY: 1–866–569–1162 

Fax: 703–738–4929 

Email: nkudic@info.niddk.nih.gov 

Internet: www.urologic.niddk.nih.gov 

The National Kidney and Urologic Diseases Information 

Clearinghouse (NKUDIC) is a service of the National Institute 

of Diabetes and Digestive and Kidney Diseases (NIDDK). The 

NIDDK is part of the National Institutes of Health of the U.S. 

Department of Health and Human 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. 

This publication may contain information about medications. 

When prepared, this publication included the most current 

information available. For updates or for questions about any 

medications, contact the U.S. Food and Drug Administration 

toll-free at 1–888–INFO–FDA (1–888–463–6332) or visit 

www.fda.gov. Consult your health care provider for more 

information. 
NIH Publication No. 12–4807

December 2011

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