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| |    Diagnosing Urinary Tract Abnormalities: Ultrasound And Other Imaging Tests by Lynn Cates, M.D., F.A.A.P. reviewed by Laura Jana, M.D., F.A.A.P. If your child has had a urinary tract infection (UTI), she probably will need to be evaluated for an abnormality of the anatomy of her urinary tract. No abnormality is found in most children. However, since the risk of kidney damage is high in those children who do a have problem, this evaluation is important. The most common tests include: Ultrasound (or ultrasonography) of the urinary tract is very similar to ultrasound performed during pregnancy, except instead of looking at the fetus, the urinary tract is viewed. The test, which involves bouncing sound waves off tissues, is safe, noninvasive (that is, it does not require any tubes to be inserted into your child's bladder or veins), and can be very helpful in identifying some anatomic problems, particularly some indications of reflux such as swelling of the tubes (ureters) that connect the bladder with the kidneys. It does not require exposure to any radiation, is easy to perform, and is less expensive than other tests. Its main disadvantage, however, is that it does not detect reflux or renal scarring as well as some other imaging procedures. Since this test is so safe and easy to perform, ordinarily healthcare providers are quick to use it to evaluate a child who is not responding as rapidly as expected to antibiotic treatment, and as the initial screening tool after the first urinary tract infection with fever in all infants and young children. Voiding cystourethrogram (VCUG is a good test for seeing if urine refluxes (that is, travels back up toward the kidneys) from the bladder (also known as vesicoureteral reflux or VUR), and if so, how badly. This test is performed by inserting a small rubber tube (or catheter) through the child's urethra into her bladder and then taking x-rays while contrast material (or dye) is introduced into the bladder. This dye goes wherever urine flows, so it shows the inner outline of the bladder, and if urine refluxes back up toward the kidneys through the ureters, it demonstrates the extent of the reflux as well as any swelling or blockage of the system. An important part of this study is to examine the urinary tract while the child is actually urinating since some children have reflux only while they are urinating. A radiologist can watch this process on a television-like apparatus using a live action form of x-ray called fluoroscopy. This test is indicated for all children under five years who have a urinary tract infection, in all children who have a fever with their urinary tract infection, and in all girls who have had two or more infections. Your child may have some discomfort when she urinates for a short time after a VCUG since the catheter inserted into her urethra may cause some mild irritation. Another disadvantage of this test is that exposes her to some radiation, although newer equipment has markedly decreased the amount of radiation exposure. Despite these disadvantages, there is no question that the risk of permanent kidney damage from leaving a urinary tract abnormality undetected far outweighs the temporary discomfort of the catheter, and the potential risk that a small dose of radiation could cause any long-term problem. Renal scan (or radionuclide cystography or RNC) is a test that may be performed to detect urinary tract abnormalities such as reflux and kidney scarring. This test requires the injection of a tiny amount of radioactive material into your child's vein. Although it generally exposes your child to somewhat less radiation than a VCUG, it is not able to pick up reflux as well and it does not show abnormalities of her bladder or urethra. However, it is better than either ultrasound or VCUG for detecting kidney scarring. Intravenous pyelogram (IVP) is an x-ray study of the urinary tract that entails giving dye through the vein (IV). The dye is concentrated by the kidneys and excreted through the urine. The dye in the urine makes the urinary tract show up very well on x-ray. It used to be an important test for evaluating the anatomy of the urinary tract, but it is not used very often any more because other tests such as ultrasounds and scans require less exposure to radiation. Computerized axial tomography (CAT- or CT-scan) or magnetic resonance imaging (MRI) studies can be used when more detailed evaluations of the anatomy of the urinary tract and surrounding structures are required. When these tests are needed The American Academy of Pediatrics recommends that any child age two months to two years who has a first urinary tract infection with fever have a sonogram and that two other studies, a voiding cystourethrogram (VCUG) and a radionuclide cystography, be strongly considered (American Academy of Pediatrics, The Diagnosis, Treatment, and Evaluation of the Initial Urinary Tract Infection in Febrile Infants and Young Children. Pediatrics. 1999;103:843-852; www.aap.org). It also recommends that the child stay on either full or partial (prophylactic) doses of antibiotics until these studies have been performed because, if the child has an abnormality of her urinary tract, she is at risk for more urinary tract infections, which carry with them the risk of causing permanent damage to her kidneys. In older girls, some experts wait until the second infection (if the first was mild and not likely to involve the upper tract), but most agree that boys should be evaluated after their first episode no matter what age. All children should have at least an ultrasound if they do not respond as expected to appropriate antibiotic treatment. If abnormalities are detected, your child's healthcare provider will recommend that at least one of these tests be repeated until the abnormality goes away or is surgically repaired.
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