Diagnosis

A urine test can reveal whether your child has a UTI. Other tests may be necessary, including:

• Kidney and bladder ultrasound. This imaging method uses high-frequency sound waves to produce images of the kidney and bladder. Ultrasound can detect structural abnormalities. This same technology, often used during pregnancy to monitor fetal development, may also reveal swollen kidneys in the baby, an indication of primary vesicoureteral reflux.

• Specialized X-ray of urinary tract system. This test uses X-rays of the bladder when it's full and when it's emptying to detect abnormalities. A thin, flexible tube (catheter) is inserted through the urethra and into the bladder while your child lies on his or her back on an X-ray table. After contrast dye is injected into the bladder through the catheter, your child's bladder is X-rayed in various positions.

  Then the catheter is removed so that your child can urinate, and more X-rays are taken of the bladder and urethra during urination to see whether the urinary tract is functioning correctly. Risks associated with this test include discomfort from the catheter or from having a full bladder and the possibility of a new urinary tract infection.

• Nuclear scan. This test uses a tracer called a radioisotope. The scanner detects the tracer and shows whether the urinary tract is functioning correctly. Risks include discomfort from the catheter and discomfort during urination.

Grading the condition

After testing, doctors grade the degree of reflux. In the mildest cases, urine backs up only to the ureter (grade I). The most severe cases involve severe kidney swelling (hydronephrosis) and twisting of the ureter (grade V).