Inflammations of the urinary tract in children

Associate Professor Milivoj Jovančević, MD, PhD, paediatrician

Normal urine does not contain bacteria. However, bacteria may at times enter the urinary tract from the outside, from the skin surrounding the anus and genitalia. Should bacteria enter the urinary tract – be it externally, through the urethra, or through blood – a healthy urinary system will destroy them, thus preventing inflammations. However, in some cases, the bacteria manage to survive and multiply. For instance, children who withhold urine (postponing urination) are more likely to suffer from urinary tract inflammations. Regular urination “washes away” bacteria and helps keep the urinary tract sterile. Prolonged withholding enables the bacteria to multiply and cause diseases. Furthermore, prolonged withholding of the urine and lengthy contractions of the muscle that releases the urine prevent its full release, which means the bladder is sometimes not entirely emptied. This can lead to the development of infections.

Inflammations are common during the summer, when heat causes the body to “preserve” water. This leads to a decrease in urine production: the urine itself becomes thick and dark, and the urination is less frequent. A similar problem occurs during illnesses accompanied by fever, diarrhoea or vomiting. In cases like this, the body is dehydrated, which means less urine is produced. This gives the bacteria in the urine time to multiply and cause an inflammation. A child who has recently recovered, for example, from a viral illness, may soon develop a fever, without any additional symptoms. The spread of bacteria is facilitated not only by a reduced frequency of urination, but also by the weakening of the immune system caused by the previous illness.

In rare cases, there may be inborn obstacles to the flow of urine, such as a narrow renal pelvis or beginning of the urethra. This causes the urine to linger in the area above the narrowing, which means the urinary tract cannot be rinsed normally.

In some cases, the problem lies with an inborn urinary bladder dysfunction – the so-called neurogenic bladder.

Other conditions facilitate the development of bacteria in the urinary tract. Each instance of withholding the urine in any part of the tract or retracting the urine back to the kidney significantly increases the risk of infection. The urine is most commonly retracted from the bladder towards the ureter. This can happen once the bladder has become full or during urination, when the contraction of the bladder muscles additionally increases the bladder pressure. This creates a vesicoureteral flux, which causes the urine to flow backward, from the bladder into the ureters. In most cases, the reflux is mild, causing only a small amount of urine to return to the kidneys; however, the amount can also be quite large which causes considerable dilation of the ureters and the renal pelvis. Milder degrees of reflux disappear spontaneously, while more severe ones require surgical treatment. In any case, it is extremely important to prevent the reappearance of urinary tract inflammations as they can cause permanent damage to the kidney tissue by scarring it. Reflux diagnosed at an early stage has a greater chance of disappearing spontaneously; the possibility of preventing kidney scarring is also higher.

In more than 80% of cases of urinary tract inflammation in children, the causal agent is Escherichia coli. There is also a certain genetic predisposition of the urinary tract mucosa towards this type of bacterial infection; the specific structure of the mucosa makes it easy for Escherichia coli to latch on and multiply.

What are the symptoms of urinary tract inflammation in children?

During the infant’s first days and months, symptoms of severe urinary tract infections are generally quite sparse. At this earliest age, resistance to infections is very small as the immune system has not matured enough to fight back by activating inflammation processes. Inflammation symptoms are therefore rare: for instance, high fever, signs of urinary dysfunction (burning sensation) and pain are usually absent. The only tell-tale signs of infection are general malaise, a halt in weight gain, anxiety, loss of appetite, vomiting, diarrhoea-like stool or prolonged infant jaundice. The aforementioned traits of the immune system allow the bacteria to multiply and spread in a relatively undisturbed and rapid manner: first along the entire urinary tract and then possibly in the blood system which allows them to spread throughout the entire body. To avoid this life-threatening situation, the inflammation needs to be identified, and treatment applied as soon as possible.

Older children experience fever, frequent urination of smaller amounts of urine, frequent feelings of a full bladder accompanied by the urge to urinate, a burning sensation during urination and pain in the kidney area. The pain can also occur in the front, below the ribs, or spread towards the shoulders. High shaking fever indicates the possible entry of the bacteria from the urinary tract into the blood system and demands special attention and the immediate commencement of treatment. Fever and pain in the kidney area do not accompany inflammations of the urinary bladder (they are indications that the inflammation has spread to the kidneys).

Urinary tract inflammations often cause the urine to become turbid and to develop an unpleasant odour.

 What to do in the event of inflammation

 If you suspect urinary tract inflammation, contact your physician. Only laboratory tests can determine the existence and degree of the inflammation. The urine is usually tested for inflammatory cells (leukocytes) and blood (erythrocytes), as well as bacteria (urine culture and antibiogram). Additional blood tests are mostly necessary with younger children, and in the case of more pronounced symptoms of inflammation, such as fever and pain. If urinary tract inflammation has been established, treatment with antibiotics will commence without delay (there is no need to wait for the urine culture test results). It is extremely important to gain proper and thorough information on how to correctly gather urine for the test, how to administer treatment and which signs to respond to.

What to do after the inflammation

 Successful treatment will surely be followed by periodic urine and urine culture tests in order to identify signs of a possible recurrence of the inflammation. Considering the high frequency of inborn anomalies of the urinary tract, other tests will be necessary to exclude their possibility. Unfortunately, there is no single test to exclude all possible causes, so several tests will probably be necessary, such as kidney ultrasound, bladder x-ray (miction cystourethrography) and kidney scintigraphy. Ultrasound is used to exclude major anomalies. The x-ray excludes reflux (nowadays, this can also be established with ultrasound), while dynamic scintigraphy provides an estimate of the kidney tissues (reveals possible scarring and measures their function).

In the event of inborn anomalies of the urinary tract or recurrent inflammations, the doctor is likely to recommend a smaller dose of medicine in the evening, in order to prevent another infection. Why is the medicine (so-called prophylaxis) administered in the evening? Because less urine is created during the night and is retained in the bladder for a longer period, which creates favourable conditions for inflammations to develop.

In addition to regular check-ups, a urine and urine culture test should be done as soon as possible if the child shows symptoms of a recurring infection, such as a fever not accompanied by other symptoms of illness (signs of a cold) or an unpleasant smell of urine.

This helps prevent extensive infections that permanently damage the kidneys, leaving them scarred. After a year or two of this type of protection, milder forms of reflux will spontaneously disappear. If more severe forms of inflammation are successfully avoided, there will be no permanent consequences, and the child’s growth and development will continue unhindered.