When the ureters enter the bladder, they travel through the wall of the bladder for a distance in such a way that they create a tunnel so that a flap-like valve is created inside the bladder. This valve prevents urine from backing-up into the ureters and kidneys.

In some children, the valves may be abnormal or the ureters in the bladder may not travel long enough in the bladder wall, which can cause vesicoureteral reflux. Vesicoureteral reflux is a condition that allows urine to go back up into the ureters and kidneys causing repeated urinary tract infections. The reflux of urine exposes the ureters and kidney to infection from bacteria and high-pressure, which is generated by the bladder during urination.  If left untreated, urinary infections can cause kidney damage and renal scarring with the loss of potential growth of the kidney and high blood pressure later in life.

Vesicoureteral reflux is treated with antibiotics, and in severe cases surgically.

Cystography is a detailed study of the bladder, which uses a dye and X-rays. A catheter is inserted into the bladder in which the dye flows. When the bladder is full, the catheter is removed and the X-rays are taken. X-rays are also taken when the bladder is empty. The test is performed to check for the integrity of the bladder, determine the cause of infections and check for tumors or stones.