Causes

Your urinary system includes your kidneys, ureters, bladder and urethra. All play a role in removing waste products from your body via urine.

Tubes called ureters carry urine from your kidneys down to your bladder, where it is stored until it exits the body through another tube (the urethra) during urination.

Vesicoureteral reflux can develop in two types, primary and secondary:

• Primary vesicoureteral reflux. Children with primary vesicoureteral reflux are born with a defect in the valve that normally prevents urine from flowing backward from the bladder into the ureters. Primary vesicoureteral reflux is the more common type.

  As your child grows, the ureters lengthen and straighten, which may improve valve function and eventually correct the reflux. This type of vesicoureteral reflux tends to run in families, which indicates that it may be genetic, but the exact cause of the defect is unknown.

• Secondary vesicoureteral reflux. The cause of this form of reflux is most often from failure of the bladder to empty properly, either due to a blockage or failure of the bladder muscle or damage to the nerves that control normal bladder emptying.