Vesicoureteral  reflux is the abnormal flow of urine from your bladder back up the tubes (ureters) that connect your kidneys to your bladder. Normally, urine flows only down from your kidneys to your bladder.

Vesicoureteral reflux is usually diagnosed in infants and children. The disorder increases the risk of urinary tract infections, which, if left untreated, can lead to kidney damage.

Vesicoureteral reflux can be primary or secondary. 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. Secondary vesicoureteral reflux occurs due to a urinary tract malfunction, often caused by abnormally high pressure inside the bladder.

Children may outgrow primary vesicoureteral reflux. Treatment, which includes medication or surgery, aims at preventing kidney damage.