Urinary Tract Infection in Children


Urinary tract infection is a fairly common disease in children. It is caused by bacteria entering the urethra and bladder. When the bacteria stop there it is called bladder catarrh. The bacteria spread to the kidneys and the renal pelvis is called renal pelvic inflammation.

Children who have a urinary tract infection are treated with antibiotics, whether they have cystitis or renal pelvic inflammation. If kidney pelvic inflammation is not treated, there is a risk of kidney damage or sepsis, also called blood poisoning, which can be life-threatening.

Symptoms of urinary tract infection in children

Children with urinary tract infection may have one or more different symptoms of either bladder catarrh or pelvic inflammation.

If the child has a bladder catarrh, it is common to

  • it stings when the baby is peeing
  • the child often needs to pee
  • the child has a hard time keeping tight
  • there is little  blood in the urine
  • the child has  a stomach ache
  • the urine smells bad.

In the case of kidney pelvic inflammation, the child usually

  • have high fever
  • feel sick and vomit
  • feeling really sick
  • be difficult to get in touch with.

Children older than three years can sometimes have side or lower back pain.

Difficult to detect symptoms in young children 

In children younger than two years, the symptoms of cystitis can be difficult to detect.
It can also be difficult to distinguish cystitis from renal pelvic inflammation, as the symptoms are usually less clear the younger the child is. 

Infants with urinary tract infections usually have a fever and lower appetite, and it can sometimes be the only thing noticed in the baby. 

Sometimes the symptoms may be due to something else 

If a boy thinks it is burning and feels uncomfortable when he is peeing, it may be due to an infection under the foreskin. In a girl, the cause may be a fungal infection or some other irritation in the mucosa of the vagina. The symptoms can also be due to an irritation in the urethra that usually passes by itself.

Red or pink urine may be due to the child-eating something that colors the urine, such as beetroot. Brick red in the diaper of infants is usually due to salts being temporarily excreted in the child’s urine, which is completely harmless. 

Smelly urine may be due to fluid deficiency or something the child has eaten. 

Bacteria that do not cause any problems 

It also happens that children have bacteria in the urine without any symptoms, so-called asymptomatic bacteriuria, ABU. These bacteria can sometimes give off smelly urine, but no other inconvenience. They protect the urinary tract from more aggressive bacteria and are usually not treated with antibiotics. 

When should I seek care?

If the child is over two years old and has symptoms suggestive of bladder catarrh, you should contact a health care center or emergency room. If it is evening or night, you can wait until the next day. For children under the age of two, you should seek care directly at a health center, emergency room or emergency room.

If the child, regardless of age, has symptoms suggestive of renal pelvic inflammation, you should also seek treatment directly at a health care center, emergency room or emergency room.

You can seek care at any reception you want throughout the country.

Treatment of urinary tract infection in children

Children who have a urinary tract infection are treated with antibiotics. Then the child usually gets better quickly.

Symptoms of bladder catheters usually disappear after one or two days.

When treating renal pelvic inflammation, the fever is usually gone after two to three days, but the child may feel tired for a long time. If the child still has a fever after a few days of treatment, more examinations need to be done.

Children under one year who have renal pelvic inflammation often need hospital care. 

The medication children are given for cystitis or renal pelvic inflammation is usually taken by mouth. However, children who are vomiting, or have impaired blood circulation, may need to get the drug directly into the blood for any day.

Read more about giving medicine to children and caring for temporarily ill children at home.

Different types of antibiotics for recurrent infections

A child who gets recurrent urinary tract infections may get different types of antibiotics from time to time. There are several reasons for that. Different antibiotics can help against different types of bacteria. 

If the child has recently received antibiotics, the risk is greater than the bacteria that cause the new infection is resistant, resistant, to the preparation that has just been used. Then the doctor may choose another type of antibiotic.

Preventive treatment of urinary tract infection in children

A child who has had multiple urinary tract infections can sometimes receive long-term treatment with a low dose of antibiotics. It is called prophylaxis and prevents bacteria from entering the urinary tract. The low dose should prevent other bacteria present in the body from being affected.

What can I do for myself?

If the child has had one or more urinary tract infections, you want to avoid it from happening again. The best way to avoid urinary tract infection is to have the baby pee regularly and take the time to pee every time. Good times can be, for example, when the child comes home from pre-school, after dinner and just before bedtime. In this way, any bacteria in the urinary tract are rinsed out before they can start an infection. 

If the child has easy urinary tract infections, it may be because there is some urine left in the bladder after it has been peeing. Then let the baby pee, get up for a short while and then sit down again and try to pee the last one. 

It is common for children who have recurrent urinary tract infections also to have constipation. Constipation helps to make the bladder drain worse and can cause the child to stay too long between the cushions. It can lead to both urinary tract infections and other bladder problems, such as urinary leakage.

Avoid washing the abdomen too much 

Skin protection from harmful bacteria can be impaired if the abdomen is washed with soap. The mucous membranes can become irritated which can cause similar symptoms as cystitis. If the child’s abdomen needs to be washed, it is possible to use plain water, perfume-free wash cream intended for the abdomen, baby oil or ordinary olive oil.

Advice that is not scientifically proven

There are many other tips on how to avoid urinary tract infection. Many of the councils do not have scientific support. 

For example, cranberry juice has not been shown to prevent urinary tract infection. But some feel that they have been helped by it or other preventative advice, such as making sure girls dry themselves after toilet visits in such a way that poop does not come into contact with the urethra or using cotton underwear and avoiding tightness tight pants. 

Also, there is no scientific support that urinary tract infection is caused by poor hygiene, bathing or cooling, although many find it easier to get bladder catarrh if they get cold.

What happens in the body?

This is how the urinary tract works

The urine is formed in the kidneys to carry away substances that the body does not need. It flows from the kidneys down through the ureters and collects in the bladder, to eventually continue out through the urethra. 

The transition between the ureter and the bladder acts as a valve that prevents the urine from flowing back into the kidneys. 

In the wall of the bladder, there are muscles that cannot be controlled with the will. When the bladder is stretched to a certain limit, the muscles contract and compress the bladder so that the pressure increases – you become pissed off. 

Around the upper part of the urethra, below the bladder, are muscles that can be controlled with the will. Children usually learn it at the age of three. With the help of these muscles, you can keep up when you are in need of a kiss. When they relax, the urethra opens and the urine flows out. 

The function of the kidneys is usually fully developed already at the age of two.

Read more about kidneys and urinary tract.

This happens in case of a urinary tract infection

In the event of a urinary tract infection, bacteria enter the bladder via the urethra. If the urinary bladder is not completely emptied, the bacteria have a greater chance of getting attached and spreading in the urinary tract. When the bacteria in the bladder multiply rapidly, it usually becomes an infection. It is called cystitis, the most common form of urinary tract infection. 

A common cause of recurrent urinary tract infections is that the child completely empties the bladder or pauses too rarely. Bacteria that happen to enter the bladder can then begin to multiply in the remaining urine and cause infection. 

It is more uncommon for the bacteria to migrate to the kidneys and cause renal pelvic inflammation. The reason why the bacteria can spread can be a congenital trait in the urinary tract, which makes it easier for bacteria to progress, or that it is a type of bacteria that gets up into the kidney more easily.

Renal pelvic inflammation usually heals completely when the child is treated with antibiotics. Rarely, renal pelvic inflammation can cause kidney damage.

The boys’ longer urethra provides some protection

Urinary tract infection is most common in boys up to six months of age, but after one year of age, it is more common in girls. This is because boys have longer urethra and the bacteria do not reach the bladder as easily as girls.

In infants, it is more common than urinary tract infection leads to renal pelvic inflammation.

Bacteria of different kinds 

There are different types of bacteria that can cause urinary tract infection. The most common are coliform bacteria, which are always present in the intestine. However, staphylococcal bacteria and other bacteria from the skin can also cause an infection, although less common. The bacteria move to the urethra via the skin and mucous membranes of the genital area. 

Easier to get new urinary tract infection after antibiotics 

All treatment with antibiotics affects the natural bacterial flora that is there to protect the body. Therefore, it may be easier to get a urinary tract infection after an antibiotic course, even if the cure is taken against other infections.

Sometimes the child’s urinary tract can cause infections

Most children who get a urinary tract infection have urinary tracts that work properly. But some children who get kidney pelvic inflammation have urinary tract which makes it easier for bacteria to spread.

The most common is so-called reflux, which means that the valve at the transition between the ureter and the bladder releases urine from the bladder up to the kidney. It makes it easier for bacteria to reach the kidney. 

Some children have dilated the renal pelvis on one or both sides. This may be due to a so-called constriction on the ureter, and it will take longer for the urine to drain to the bladder. Bacteria that have made their way up to the renal pelvis then become easier to stay there. 

In boys, the constriction can sit in the urethra. This makes it harder to empty the bladder when the boy is peeing, and bacteria can more easily remain. 

Some of these changes disappear by themselves as the child grows, but sometimes the urinary tract needs surgery to get rid of the problems.


In renal pelvic inflammation, part of the kidney is inflamed and swollen, and it can take up to six months before it is healed. Inflammation usually heals completely, but some children suffer permanent damage in the form of scarring. If the damage is small, the function of the kidneys is not affected because they have large reserve capacity. 

If the injury is greater, renal function may be impaired and the child may have high blood pressure in the future. Then the child needs to go on checks during growing up. But most children with kidney damage have no noticeable symptoms, and daily life is usually not affected at all. 

If the child has a bladder catarrh, the risk of future complications is very small.


In order for it to be certain that it is a urinary tract infection, the child may submit a urine sample. This is mainly done to find out if the problems are due to bacteria in the urine. A urine culture is also done to find out which bacterium is involved and whether it is resistant, resistant, to antibiotics. For example, if the child has recently been abroad, the risk is greater than the infection is caused by resistant bacteria.

Urine and urine sample

The urine sample is usually examined first with the urinary tract. When the specimen is examined with a urine stick, the stick is first dipped in the urine. The urethra can give information directly if there are bacteria in the urine but does not show what kind of bacteria it is. Sometimes there may be bacteria even though the stick does not show it. The urethra also shows if there are very white blood cells in the urine which may be a sign of urinary tract infection. 

Then the urine culture is done. After it is sent to a laboratory, it takes one to three days for the answer to arrive. The cultivation gives information about what kind of bacteria it is and how much bacteria it is. It also shows if the antibiotics that are usually used will help or if the bacterium is resistant to them.

When to give urine samples to children

In order for the urine sample to be as safe as possible, the child should preferably not have coughed for four hours or longer when the sample is taken. It is best to take it when the baby is peeing in the morning.
Ideally, it should be a so-called mid-beam test, that is, the child kisses a small splash before the urine is caught. This reduces the risk of other bacteria from the genital area. 

A mid-beam sample can be obtained even if the baby has a diaper, but patience and attention may be needed to catch the urine when it arrives. It is usually easier to do it at home than at reception. Small children who use diapers cannot urinate on an urge. But often one can get a urine sample by sitting with the baby without diapers in the knee, and catching the urine when the baby is peeing. 

You can get a clean can for urine samples at the health center or buy at a pharmacy. You should leave the urine sample to the health care center or hospital as soon as possible, but it can be stored in the refrigerator for 24 hours. The sample also needs to be kept cool when transported, so when you bring the sample you can have it in a plastic bag along with some ice cubes.

Urine from bag or panty

At some clinics, a self-adhesive pouch is used around the penis or pubic lips to collect urine from diapers, so-called pouch samples. 

Many children get red and irritated skin from the adhesive of the bag. A gentler way of collecting urine is to use a type of panty protection that is put into the diaper. You change your pantyhose every half hour to get a cleaner sample. When the child has kissed, the urine is crushed out of the panty. It is usually enough for the baby to pee once to get enough urine. 

Urine from the bag or panty protector can be used for tests with urine sticks, but should not be used for urine production as it is common for the urine to become contaminated. The bacterial content in the urine sample becomes high even if the child does not have a urinary tract infection.

Urine directly from the bladder

The safest method to avoid a contaminated sample is that urine is taken directly from the bladder through a so-called blue puncture. A thin needle is then inserted through the skin and further into the bladder. The sting is harmless and feels a bit like taking a blood sample from a blood vessel. Blueprint is mainly done on infants, by a doctor or other trained staff. 

Investigation of recurring blue cataracts

Some children have recurring blue cataracts. Then various examinations are sometimes done to find out how the bladder works. With the help of ultrasound, it is possible to see if there is urine left in the bladder after the baby has kissed, which can lead to bladder catarrh.

If the child is suspected of having renal pelvic inflammation

If the doctor suspects that a child has renal pelvic inflammation, the child may have a blood test for a so-called CRP test, also called rapid lowering. In renal pelvic inflammation, the CRP value is often high, but in a bladder catheter, it is normal or only slightly elevated.

Ultrasound of the urinary tract

Most children with urinary tract infections have urinary tracts that work properly. But some children with pelvic inflammation have urinary tract infections that make it easier for bacteria to spread. 

All children with pelvic inflammation are usually examined with ultrasound to assess the size of the kidneys and to exclude signs of urinary tract or urethra.


It is possible to see how the kidney is affected by an infection by means of a study called scintigraphy. A fluid is injected into the bloodstream and gets stuck in the parts of the kidney that work properly. With the help of a special camera, gamma camera, areas with reduced functions are clearly visible. If the kidney proves to work in all parts, there is usually no risk of the child having reflux, and the bladder does not need to be x-rayed.

If the first scintigraphy shows changes in any of the kidneys, this examination is done again, six months to one year after the infection. If, after such a long time, areas of the kidney with impaired function are still visible, it means that there is an injury that can be permanent.

X-ray of the bladder, MUCG 

X-ray examination of the bladder, called MUCG, is primarily done to look for reflux, and in boys, a urethra narrowing. A thin tube, catheter, is passed through the urethra to the bladder which is filled with contrast fluid. On the X-ray, it is possible to see if the fluid flows back to the kidney. 

Since bladder X-ray shows the clearest results when the baby is kissing, the baby may not be asleep during the time. The examination usually does not hurt, but can feel uncomfortable. Sometimes the child can receive sedative medication before the examination.

Other methods of investigation

Sometimes other methods may be needed to find the cause of recurrent urinary tract infections. It may be, for example, computed tomography, which is a more detailed form of X-ray, or magnetic camera examination.

If the cause of the infection can be found in the urethra, the child may need to be examined with cystoscopy. The study uses either a straight narrow tube or a narrow tube-like instrument. The instrument acts as a kind of binoculars with illumination and is called a cystoscope. The child is anesthetized during the examination.

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