In the first case normally the valve or sphincter keeps the bladder from emptying but sometimes they can be too tight or in the wrong position. The bladder can not be empty completely and the urine can back up and cause backpressure on the kidneys. This can cause a dilation of the kidneys named hydronephrosis which can lead to serious kidney damage. Kidney damage can appear at newborns born from in utero backpressure, or can develop during the first few months of life. Rarely this condition occurs in males, but does need to be diagnosed quickly. A weak urine stream is one clue to this problem.

Vessico-ureteral reflux (VUR) occurs where the urine tubes, called ureters, from the kidneys empty into the bladder. The urine from the bladder is prevented by one-way valve to go back up into the ureters and kidneys. The urine can go backwards and cause backpressure on the kidneys, or hydronephrosis at children which are born with immature ureter valves. Over time the backpressure can damage the kidneys.

There are very rare cases when the kidneys, or the tubes that drain them into the bladder, can develop abnormally. The urine is prevented to drain properly into the bladder and this can lead to infections.

Different radiology tests are used to look for structural problems involving the bladder and kidneys. Ultrasound is painless and non-invasive. If a structural problem with the kidneys or ureters exists, or if any hydronephrosis (back-pressure) is present ultrasound can show that. VUR or a urethral valve problem cannot be found out with an ultrasound.

Voiding Cysto-urethrogram (VCUG) is a test that involves restraining an infant or child, inserting a catheter through the urethra into the bladder, injecting a dye into the catheter, pulling out the catheter, and allowing the infant to urinate the dye back out. During the procedure x-rays are taken. If any structural problem exists can be seen on the x-ray with the help of the dye that outlines the bladder and urethra. If VUR is present the x-ray will show the dye backing up through the ureters into the kidneys. The dye does not produces damage the bladder or kidneys, and it is flushed out quickly with urinating. This test is invasive and can be painful and scary for a child but it's the one that can detect problems with the urethra and ureters. Unfortunately very little information about the kidneys is given by this test.

Intravenous pyelogram (IVP) involves injected dye through an IV into the blood stream. Outlining the structure of the kidneys on x-ray is shown by the dye that travels through the kidneys and into the urine. VUR or urethra problems can not be seen with this test.

Nuclear medicine scan shows the kidneys in such a way that checks the kidney function and checks for scars in the kidneys.

In the case of abnormality presence some tests are recommended by doctor. So an ultrasound and VCUG should be done in these instances: newborns who have a single bladder infection, infants less than one year of age who have a second bladder infection and older children who have had more than three or four infections.

A referral to a pediatric urologist or nephrologist is necessary when these tests are normal, but the child continues to have problems with infections. An IVP will be done if the specialist will decide. A surgical specialist is called urologist and a non-surgical specialist is called nephrologist. If an abnormality on these tests appear doctor may recommend a specialist for appropriate treatment.

A daily low-dose of antibiotics can be given to children who have recurrent bladder infections to control any bacteria that may get into the bladder. Prophylactic antibiotics are used when children with known anatomic abnormalities make them prone to infections, and when children without abnormalities continue to have infections despite all the above non-medical prevention. Usually children will take an antibiotic for six to twelve months and after treatment will come back to make other tests to see the result.

It is difficult for children to do these tests because they are not funny, but these can help to discover the problems which can be treated.