Urinary Tract 

Infections in Children 

National Kidney and Urologic Diseases Information Clearinghouse 

U.S. Department 

of Health and 

Human Services 

NATIONAL 

INSTITUTES 

OF HEALTH 

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—including fungi, viruses, and 

bacteria. Bacteria are the most common 

cause of UTIs. Normally, bacteria that enter 

the urinary tract are rapidly removed by the 

body before they cause symptoms. However, 

sometimes bacteria overcome the body’s 

natural defenses and cause infection. An 

infection in the urethra is called urethritis. A 

bladder infection is called cystitis. Bacteria 

may travel up the ureters to multiply and 

infect the kidneys. A kidney infection is 

called pyelonephritis. 

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 bean-shaped organs, each 

about the size of a fist and located below the 

ribs, one on each side of the spine, toward 

the middle of the back. Every minute, a 

person’s kidneys filter about 3 ounces of 

blood, removing wastes and extra water. 

The wastes and extra water make up the 

1 to 2 quarts of urine an adult produces each 

day. Children produce less urine each day; 

the amount produced depends on their age. 

The urine travels from the kidneys down two 

narrow tubes called the ureters. The urine is 

then stored in a balloonlike organ called the 

Kidneys 

Ureters 

Urethra 

Bladder 

Front view of the urinary tract 

bladder. Routinely, urine drains in only one 

direction—from the kidneys to the bladder. 

The bladder fills with urine until it is full 

enough to signal the need to urinate. In children, the bladder can hold about 2 ounces of 

urine plus 1 ounce for each year of age. For 

example, an 8-year-old’s bladder can hold 

about 10 ounces of urine. 

When the bladder empties, a muscle called 

the sphincter relaxes and urine flows out of 

the body through a tube called the urethra at 

the bottom of the bladder. The opening of 

the urethra is at the end of the penis in boys 

and in front of the vagina in girls. 
 

 

2 Urinary Tract Infections in Children 

Side view of the male urinary tract 

Urethra 

Kidney 

Bladder 

Ureter 

Side view of the female urinary tract 

What causes UTIs? 

Most UTIs are caused by bacteria that live 

in the bowel. The bacterium Escherichia 

coli (E. coli) causes the vast majority of 

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, or 

refluxing, toward the kidneys, and urination 

washes microbes out of the body. Immune 

defenses also prevent infection. But despite 

these safeguards, infections still occur. 

Certain bacteria have a strong ability to 

attach themselves to the lining of the urinary 

tract. 

Children who often delay urination are more 

likely to develop UTIs. Regular urination 

helps keep the urinary tract sterile by flushing away bacteria. Holding in urine allows 

bacteria to grow. Producing too little urine 

because of inadequate fluid intake can 

also increase the risk of developing a UTI. 

Chronic constipation—a condition in which 

a child has fewer than two bowel movements 

Bladder 

Kidney 

Ureter 

Urethra 

Vagina 

a week—can add to the risk of developing a 

UTI. When the bowel is full of hard stool, 

it presses against the bladder and bladder 

neck, blocking the flow of urine and allowing 

bacteria to grow. 

Some children develop UTIs because they 

are prone to such infections, just as other 

children are prone to getting coughs, colds, 

or ear infections. 

How common are UTIs in 

children? 

Urinary tract infections affect about 3 percent of children in the United States every 

year. UTIs account for more than 1 million 

visits to pediatricians’ offices every year.1

1Freedman, AL. Urinary tract infections in children. 

In: Litwin MS, Saigal CS, eds. Urologic Diseases in 

America. U.S. Department of Health and Human 

Services, Public Health Service, National Institutes of 

Health, National Institute of Diabetes and Digestive 

and Kidney Diseases. Washington, D.C.: U.S. 

Government Printing Office; 2007. NIH publication 

07–5512:439–458. 
 

Who is at risk for a UTI? 

Throughout childhood, the risk of having a 

UTI is 2 percent for boys and 8 percent for 

girls. Having an anomaly of the urinary tract, 

such as urine reflux from the bladder back 

into the ureters, increases the risk of a UTI. 

Boys who are younger than 6 months old 

who are not circumcised are at greater risk 

for a UTI than circumcised boys the same 

age.1 

Are UTIs serious? 

Most UTIs are not serious, but some infections can lead to serious problems, such 

as kidney infections. Chronic kidney 

infections—infections that recur or last 

a long time—can cause permanent damage, including kidney scars, poor kidney 

growth, 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. 

In some children, a UTI may be a sign of 

an abnormality in the urinary tract that 

leads to repeated problems. Young children 

are at the greatest risk for kidney damage 

from UTIs and defects in the urinary tract. 

Children with UTIs should receive careful evaluation with prompt treatment. The 

evaluation may include an examination of 

the urinary tract using imaging equipment. 

Because UTIs are less common in boys after 

the first 4 weeks of life, boys with a UTI 

should be assumed to have an abnormality of 

the urinary tract until proven otherwise. 

What are the signs and 

symptoms of a UTI? 

Symptoms of a UTI range from slight burning with urination or unusual-smelling urine 

to severe pain and high fever. A child with 

a UTI may also have no symptoms. A UTI 

causes irritation of the lining of the bladder, urethra, ureters, and kidneys, just as 

the inside of the nose or the throat becomes 

irritated with a cold. In infants or children 

who are only a few years old, the signs of a 

UTI may not be clear because children that 

young cannot express exactly how they feel. 

Children may have a high fever, be irritable, 

or not eat. 

On the other hand, children may have only a 

low-grade fever; experience nausea, vomiting, and diarrhea; or just not seem healthy. 

Children who have a high fever and appear 

sick for more than a day without signs of a 

runny nose or other obvious cause for discomfort should be checked for a UTI. 

Older children with UTIs may complain 

of pain in the middle and lower abdomen. 

They may urinate often. Crying or complaining that it hurts to urinate and producing 

only a few drops of urine at a time are other 

signs of a UTI. Children may leak urine into 

clothing or bedsheets. The urine may look 

cloudy or bloody. If a kidney is infected, 

children may complain of pain in the back or 

side below the ribs. 

Parents should talk with their health care 

provider if they suspect their child has a UTI. 

How are UTIs diagnosed? 

Only a health care provider can determine 

whether a child has a UTI. 

A urine sample will be collected and examined. The way urine is collected depends on 

the child’s age: 

• If the child is not yet toilet trained, the 

health care provider may place a plastic 

collection bag over the child’s genital 

area. The bag will be sealed to the skin 

with an adhesive strip. If this method 

is used, the bag should be removed 

right after the child has urinated, and 

the urine sample should be processed 

3 Urinary Tract Infections in Children 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

immediately. Because bacteria from the 

skin can contaminate this sample, the 

methods listed below are more accurate. 

• A health care provider may need to pass 

a small tube called a catheter into the 

urethra of an infant. Urine will drain 

directly from the bladder into a clean 

container. 

• Sometimes the best way to collect a 

urine sample from an infant is by placing a needle directly into the bladder 

through the skin of the lower abdomen. 

Getting urine through a catheter or 

needle will ensure that the urine collected does not contain bacteria from 

the skin. 

• An older child may be asked to urinate 

into a container. The sample needs to 

come as directly into the container as 

possible to avoid picking up bacteria 

from the skin or rectal area. 

Some of the urine will be examined with a 

microscope. If an infection is present, bacteria and sometimes pus will be found in the 

urine. A urine culture should also be performed on some of the urine. 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. 

The reliability of the culture depends on how 

the urine is collected and how long the urine 

stands before the culture is started. If the 

urine sample is collected at home, it should 

be refrigerated as soon as it is collected. The 

container should be carried to the health 

care provider or lab in a plastic bag filled 

with ice. 

The health care provider may also order a 

sensitivity test, which tests the bacteria for 

sensitivity to different antibiotics to see which 

medication is best for treating the infection. 

How are UTIs treated? 

Most UTIs are caused by bacteria, which are 

treated with bacteria-fighting medications 

called antibiotics or antimicrobials. While a 

urine sample is sent to a laboratory, the health 

care provider may begin treatment with an 

antibiotic that treats the bacteria most likely 

to be causing the infection. Once culture 

results are known, the health care provider 

may decide to switch the child’s antibiotic. 

The choice of medication and length of treatment depend on the child’s history and the 

type of bacteria causing the infection. When 

a child is sick or unable to drink fluids, the 

antibiotic may need to be put directly into 

the bloodstream through a vein in the arm or 

hand or be given as an injection. Otherwise, 

the medication—liquid or pills—may be given 

by mouth. The medication is given for at least 

3 to 5 days and possibly for as long as several 

weeks. The daily treatment schedule recommended depends on the specific medication 

prescribed: The schedule may call for a single 

dose each day or up to four doses each day. 

In some cases, a child will need to take the 

medication until further tests are finished. 

After a few doses of the antibiotic, a child may 

appear much better, but often several days 

may pass before all symptoms are gone. In 

any case, the medication should be taken for 

as long as the health care provider recommends. Medications should not be stopped 

because the symptoms have gone away. 

Infections may return, and bacteria can resist 

future treatment if the medication is stopped 

too soon. 

If needed, the health care provider may 

recommend an appropriate over-the-counter 

medication to relieve the pain of a UTI. A 

heating pad on the back or abdomen may 

also help. 

4 Urinary Tract Infections in Children 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

What tests may be needed 

after the UTI is gone? 

Once the infection has cleared, more tests 

may be recommended to check for abnormalities in the urinary tract. Repeated infections in an abnormal urinary tract may cause 

kidney damage. The kinds of tests ordered 

will depend on the child and the type of 

urinary infection. Because no single test can 

tell everything about the urinary tract that 

might be important, more than one of the 

tests listed below may be needed. 

• 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 certain abnormalities in the 

kidneys and bladder. However, this 

test cannot reveal all important urinary 

abnormalities or measure how well the 

kidneys work. 

• 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. The 

child’s 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-ray machine captures 

images of the contrast medium while the 

bladder is full and when the child urinates. 

The procedure is performed in a health 

care provider’s office, outpatient center, 

or hospital by an x-ray technician supervised by a radiologist, who then interprets 

the images. Anesthesia is not needed, but 

sedation may be used for some children. 

This test can show abnormalities of the 

inside of the urethra and bladder. The 

test can also determine whether the flow 

of urine is normal when the bladder 

empties. 

• Computerized tomography (CT) scan. 

CT scans use a combination of x rays and 

computer technology to create threedimensional (3-D) images. A CT scan 

may include the injection of contrast 

medium. CT scans require the child to 

lie on a table that slides into a tunnelshaped 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 

the body’s internal organs and soft tissues without using x rays. An MRI may 

include the injection of contrast medium. 

With most MRI machines, the child 

lies on a table that slides into a tunnelshaped device that may be open ended or 

closed at one end; some newer machines 

are designed to allow the child 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 for children 

with a fear of confined spaces. Like CT 

scans, MRIs can provide clearer, more 

detailed images. 

• 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 

5 Urinary Tract Infections in Children 
 

 

damage to cells is low. Special cameras 

and computers are used to create images 

of the radioactive chemicals as they pass 

through the 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 the blood can 

provide information about kidney function. Radioactive chemicals can also be 

put into the fluids used to fill the bladder and urethra for x ray, MRI, and CT 

imaging. Radionuclide scans expose a 

child to about the same amount or less of 

radiation as a conventional x ray. 

• Urodynamics. Urodynamic testing is 

any procedure that looks at how well 

the 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 the child calm. Most 

urodynamic tests focus on the bladder’s 

ability to hold urine and empty steadily 

and completely. Urodynamic tests can 

also show whether the bladder is having 

abnormal contractions that cause leakage. A health care provider may order 

these tests if there is evidence that the 

child has some kind of nerve damage or 

dysfunctional voiding—unhealthy urination habits such as holding in urine when 

the bladder is full. 

What abnormalities lead to 

chronic urinary problems? 

Many children who get a UTI have normal 

kidneys and bladders. But if a child has an 

abnormality, it should be detected as early 

as possible to protect the kidneys against 

damage. Abnormalities that could occur 

include the following: 

• Vesicoureteral reflux (VUR). 

Vesicoureteral reflux is the abnormal 

flow of urine from the bladder to the 

upper urinary tract. In VUR, urine 

may reflux into one or both ureters and, 

in some cases, to one or both kidneys. 

VUR that affects only one ureter and 

kidney is called unilateral reflux, and 

VUR that affects both ureters and kidneys is called bilateral reflux. 

• Urinary obstruction. Blockages to 

urinary flow can occur in many places in 

the urinary tract. The ureter or urethra 

may be too narrow or a kidney stone at 

some point stops the urine from leaving 

the body. Occasionally, the ureter may 

join the kidney or bladder at the wrong 

place and prevent urine from leaving the 

kidney in the normal way. 

• Dysfunctional voiding. Some children 

develop a habit of delaying a trip to 

the bathroom and holding their urine 

because they don’t want to leave their 

play. They may work so hard at keeping 

the sphincter muscles tight that they are 

unable to relax them at the right time. 

These children may be unable to empty 

the bladder completely. Some children 

may strain during urination. Persistent 

straining may cause increased pressure 

in the bladder that forces urine to reflux 

into the ureters. Dysfunctional voiding can lead to VUR, accidental urinary 

leakage, and UTIs. 

How are abnormalities in 

the urinary tract treated? 

Some abnormalities in the urinary tract 

correct themselves as the child grows, but 

some may require surgical correction. While 

milder forms of VUR may resolve on their 

own, one common procedure to correct 

6 Urinary Tract Infections in Children 
 

 

 

 

 

VUR is the reimplantation of the ureters. 

During this procedure, the surgeon repositions the connection between the ureters and 

the bladder so that urine will not reflux into 

the ureters and kidneys. This procedure may 

be performed through an incision that gives 

the surgeon a direct view of the bladder and 

ureters or laparoscopically. Laparoscopy is a 

procedure that uses a scope inserted through 

a small incision. 

In recent years, health care providers have 

treated some cases of VUR by injecting 

substances into the bladder wall, just below 

the opening where the ureter joins the bladder. This injection creates a kind of narrowing or valve that keeps urine from refluxing 

into the ureters. The injection is delivered 

to the inside of the bladder through a catheter passed through the urethra, so there is 

no surgical incision. Evidence of clinically 

significant obstruction may indicate the need 

for surgery. 

How can UTIs be prevented? 

If a child has a normal urinary tract, parents 

can help the child avoid UTIs by encouraging 

regular trips to the bathroom. The parents 

should make sure the child gets enough to 

drink if infrequent urination is a problem. 

The child should be taught proper cleaning 

techniques after using the bathroom to keep 

bacteria from entering the urinary tract. 

Loose-fitting clothes and cotton underwear 

allow air to dry the area. Parents should 

consult a health care provider about the best 

ways to treat constipation. 

Eating, Diet, and Nutrition 

Children with a UTI should drink as much 

as they wish and not be forced to drink large 

amounts of fluid. The health care provider 

needs to know if a child is not interested in 

drinking or is unable to drink. 

Points to Remember 

• Urinary tract infections (UTIs) 

usually occur when the body fails to 

remove bacteria rapidly from the 

urinary tract. 

• UTIs affect about 3 percent of children in the United States every year. 

• Most UTIs are not serious, but 

chronic kidney infections can cause 

permanent damage. 

• A UTI in a young child may be a 

sign of an abnormality in the urinary 

tract that could lead to repeated 

problems. 

• Symptoms of a UTI range from 

slight burning with urination or 

unusual-smelling urine to severe 

pain and high fever. A child with a 

UTI may also have no symptoms. 

• Parents should talk with their health 

care provider if they suspect their 

child has a UTI. 

Hope through Research 

The National Institute of Diabetes and 

Digestive and Kidney Diseases (NIDDK) 

sponsors several programs aimed at understanding urologic diseases in adults and 

children. The NIDDK’s Division of Kidney, 

Urologic, and Hematologic Diseases supports efforts to develop more effective 

treatments for UTIs in children caused 

by VUR. The Randomized Intervention 

for Vesicoureteral Reflux (RIVUR) is a 

multicenter trial designed to determine 

whether taking antibiotics every day is an 

effective way to prevent recurrence of UTIs 

in children with VUR. More information 

about the RIVUR study, funded under 

7 Urinary Tract Infections in Children 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

National Institutes of Health clinical trial 

number NCT00405704, can be found at 

www.cscc.unc.edu/rivur. 

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. 

For More Information 

American Urological Association Foundation 

1000 Corporate Boulevard 

Linthicum, MD 21090 

Phone: 1–800–828–7866 or 410–689–3990 

Fax: 410–689–3998 

Email: auafoundation@auafoundation.org 

Internet: www.auafoundation.org

 www.UrologyHealth.org 

Acknowledgments 

Publications produced by the Clearinghouse 

are carefully reviewed by both NIDDK scientists and outside experts. This publication 

was originally prepared in cooperation with 

the Bladder Health Council and the Pediatric 

Urology Health Council of the American 

Urological Association Foundation, in partnership with the National Association for 

Continence and The Simon Foundation for 

Continence. Linda M. Dairiki Shortliffe, M.D., 

Stanford University Medical Center, reviewed 

the updated version of the publication. 

You may also find additional information about this 

topic by visiting MedlinePlus at www.medlineplus.gov. 

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

more information. 

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U.S. DEPARTMENT OF HEALTH 

AND HUMAN SERVICES 

National Institutes of Health 

NIH Publication No. 12–4246 

November 2011 

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