Each kidney continuously filters waste from the blood to produce urine. The urine then drains through the ureters into the bladder at a low pressure. From the bladder, urine drains through the urethra to exit the body. In males, the urethra is located in the penis. In females, the urethra ends in the vulvar area (the area of the external female genital organs).
People normally have two ureters. One ureter connects the left kidney to the bladder, and the other ureter connects the right kidney to the bladder. Many birth defects of the bladder or birth defects of the ureters involve the junction where a ureter connects to the bladder. Normally the junction allows urine to flow only one way, from the kidneys to the bladder. Defects of the junction can allow urine to flow back up the ureter and sometimes into the kidneys. In addition, other defects that block the flow of urine can increase the pressure in the bladder and cause urinary reflux. Reflux can affect one side or both sides.
Doctors suspect urinary reflux if babies or young children have a urinary tract infection that is severe enough to cause fever. Usually they do ultrasonography of the urinary tract to look for abnormalities.
If the ultrasonography results are abnormal or if the child keeps having urinary tract infections, doctors may do a more complicated test called voiding cystourethrography. For voiding cystourethrography, a catheter is passed through the urethra into the bladder, a liquid that shows up on x-rays (contrast agent) is put through the catheter, and x-rays are taken before and after the child urinates.
Radionuclide cystography is similar to voiding cystourethrography except that a radioactive agent is placed in the bladder and images are taken using a nuclear scanner. This test exposes the child's ovaries or testes to less radiation than voiding cystourethrography.
Treatment of urinary reflux depends on the specific birth defect and also on the severity of the complications.
Children who have few symptoms and no complications usually do not require treatment.
Children who have frequent urinary tract infections, signs of kidney damage, or both typically need treatment. If symptoms are not too severe, doctors sometimes give children daily preventive antibiotics to prevent infection. Children with more severe symptoms usually need surgery to correct the problem and ensure urine drains properly.