The urine travels from the kidneys down two narrow tubes called the
ureters. The urine is then stored in a balloon- like organ called the bladder
(see figure 1).
In a child, the bladder can hold about 1 to 1-1/2 ounces of urine for each year of the
child's age. So, the bladder of a 4-year-old child may hold about 4 to 6 ounces (less than
1 cup); an 8-year-old can hold 8 to 12 ounces.
When the bladder empties, urine flows out
of the body through the urethra, a tube at the bottom of the bladder. The opening of the
urethra is at the end of the penis in boys (see figure 2) and in front of the
vagina in girls (see figure 3). Figure 1. Front view of urinary tract
Figure 2. Side view of male urinary tract Figure 3. Side view of female urinary tract
How does the urinary tract become infected?
Normal urine contains no bacteria (germs). Bacteria may, at times, get into the urinary
tract and the urine from the skin around the rectum and genitals by traveling up the
urethra into the bladder. When this happens, the bacteria can infect and inflame the
bladder and causes swelling and pain in the lower abdomen and side. This is called
cystitis (bladder infection). If the bacteria travel up through the ureters to the kidneys,
a kidney infection can develop.
The infection is usually accompanied by pain and fever. Kidney infections
are much more serious than bladder infections. In some children a urinary tract infection may be a sign of
an abnormal urinary tract that may be prone to repeated problems. (See What abnormalities lead to urinary problems?)
For this reason, when a child has a urinary infection, additional tests are often
recommended. (See What tests may be needed after the infection is gone?)
In other cases,
children develop urinary tract infections because they are prone to such infections, just as
other children are prone to getting coughs, colds, or ear infections. Or a child may happen
to be infected by a type of bacteria with a special ability to cause urinary tract infections.
What are the signs of urinary tract infection?
A urinary tract infection causes irritation of the lining of the bladder, urethra,
ureters, and kidneys, just like the inside of the nose or the throat becomes irritated with a cold. If your
child is an infant or is only a few years old, the signs of a urinary tract infection may not
be clear, since children that young cannot tell you just how they feel.
may have a high fever, be irritable, or not eat.
On the other hand, sometimes a child may have only a low-grade fever, experience
nausea and vomiting, or just not seem healthy. The diaper urine may have an unusual
smell. If your child has a high temperature and appears sick for more than a day without
signs of a runny nose or other obvious cause for discomfort, he or she may need to be
checked for a bladder infection.
An older child with bladder
irritation may complain of pain in the abdomen and pelvic area. Your child may urinate often. If the kidney is infected, your child may complain of
pain under the side of the rib cage (the flank) or low back pain. Crying or complaining
that it hurts to urinate and producing only a few drops of urine at a time are other signs of
urinary tract infection.
Your child may have difficulty controlling the urine and may leak
urine into clothing or bed sheets. The urine may smell unusual or look cloudy.
How do you find out whether your child has a urinary tract infection?
Only by consulting a health care provider can you find out for certain
whether your child has a urinary tract infection.
Some of your child's urine will be collected and examined. The way urine is collected
depends on how old your child is. If the child is not yet toilet trained, the health care
provider may place a plastic collection bag over your child's genital area. It will be sealed
to the skin with an adhesive strip. 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. A doctor or nurse may need to pass a small tube into
the urethra. Urine will drain directly from the bladder into a clean container through this
tube (called a catheter).
Sometimes the best way to get the urine is by placing a needle
directly into the bladder through the skin of the lower abdomen. Getting urine through the
tube or needle will ensure that the urine collected is pure.
Some of the urine will be examined under a microscope. If an infection is present,
bacteria and sometimes pus will be found in the urine. If the bacteria from the sample are
hard to see at first, the health care provider may place the sample in a tube or dish with
a substance that encourages any bacteria present to grow.
germs have multiplied, they can then be identified and tested to see which medications will provide the most
effective treatment. The process of growing bacteria in the laboratory is known as
performing a culture and often takes a day or more to complete. The reliability of the culture depends on how long the
urine stands before the culture is started. If you collect your child's urine at home, refrigerate it as soon
as it is collected and carry the container to the health care provider or lab in a plastic bag filled with ice.
How are urinary tract infections treated?
Urinary tract infections are treated with antibiotics (bacteria-fighting drugs). While a
urine sample is being examined, the health care provider may begin treatment with a drug
that treats the bacteria most likely to be causing the infection. Once culture results are
known, the health care provider may decide to switch your child to another antibiotic.
The way the antibiotic is given and the number of days that it must be taken depend in
part on the type of infection and how severe it is. When a child is sick or not able to drink
fluids, the antibiotic may need to be put directly into the bloodstream through a vein in
the arm or hand. Otherwise, the medicine (liquid or pills) may be given by mouth or by
The medicine 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 drug
prescribed: The schedule may call for a single dose each day or up to four doses each
day. In some cases, your child will need to take the medicine until further tests are
After a few doses of the antibiotic, your child may appear much better, but often several
days may pass before all symptoms are gone. In any case, your child should take the
medicine for as long as the doctor says. Do not stop medications because the symptoms
have gone away. Infections may return, and germs can resist future treatment if the drug
is stopped too soon.
Children should drink fluids when they wish. Make sure your child drinks what he or she
needs, but do not force your child to drink large amounts of fluid. The health care
provider needs to know if the child is not interested in drinking. What tests may be needed after the infection is gone?
Once the infection has cleared, additional tests may be recommended to check for
abnormalities in the urinary tract. Repeated infections in abnormal urinary tracts may
cause kidney damage. The kinds of tests ordered will depend on your 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 following tests may be needed:
.Kidney and bladder ultrasound. An ultrasound test examines the kidney and
bladder using sound waves. This test shows shadows of the kidney and bladder
that may point out certain abnormalities. However, this test cannot reveal all
important urinary abnormalities. It also cannot measure how well a kidney works.
· Voiding cystourethrogram
(VCUG). This test examines the urethra and bladder while the bladder fills and empties. A liquid that can be seen on x rays is placed
into the bladder through a catheter. The bladder is filled until the child urinates.
This test can reveal 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.
pyelogram. This test examines the whole urinary tract. A liquid that
can be seen on x rays is injected into a vein. The substance travels into the
kidneys and bladder, revealing possible obstructions.
· Nuclear scans. Tests using radioactive materials that are usually injected into a
vein to show how well the kidneys work, the shape of the kidneys, and whether
urine empties from the kidneys in a normal way. Each kind of nuclear scan gives
different information about the kidneys and bladder.
Nuclear scans expose a child
to about the same amount of radiation as a conventional x ray. At times, it can
even be less. What abnormalities lead to urinary problems? Many children who get urinary tract
infections have normal kidneys and bladders.
a child has an abnormality, it should be detected as early as possible in life to protect the
kidneys against damage. Abnormalities that could occur include the following:
· Vesicoureteral reflux. Urine normally flows from the kidneys down the ureters
to the bladder in one direction. With reflux, when the bladder fills, the urine may
also flow backward from the bladder up the ureters to the kidneys. This
abnormality is common in children with urinary infections.
· 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 urinary flow 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.
Do urinary tract infections have long-term effects?
Young children are at the greatest risk for kidney damage from urinary tract infections,
especially if they have some unknown urinary tract abnormality. Such damage includes
kidney scars, poor kidney growth, poor kidney function, high blood pressure, and other
For this reason it is important that children with urinary tract infections receive
prompt treatment and careful evaluation.