What causes vesicoureteral reflux (VUR)?

A child can be born with vesicoureteral reflux, or VUR, or it can develop over time

There are two forms of vesicoureteral reflux (VUR), primary and secondary. Primary and secondary forms of vesicoureteral reflux vary dependent on the cause of VUR in your child.

Primary VUR

When a child has primary VUR, it means that one or both of the child’s ureters, the tubes that carry urine from the kidneys to the bladder, didn’t develop properly. The ureter is too short, so the valve between the bladder and ureter that normally closes to prevent urine from flowing backward doesn’t shut the way it should.

Primary VUR is the most common kind of VUR and tends to run in families. VUR is present in about 30% of siblings with VUR¹, and in up to 50% of children whose mothers had VUR.² A child may outgrow it when the ureters lengthen and straighten during the growth process. This site provides more information on the chances of outgrowing VUR.

Secondary VUR

Secondary VUR is often the result of a urinary blockage of some kind. Sometimes this happens after your child has had numerous urinary tract infections (UTIs), which can cause the ureter to swell and prevent the normal elimination of urine. This is why it’s important to alert your doctor immediately if you suspect your child has a UTI.