What Causes Vesicoureteral Reflux?

The exact percentage of children with VUR is unknown. However estimates are that VUR occurs in about 10 of every 100 healthy children. It is not contagious. In most children, reflux is the result of a birth defect. There is an shorter than normal attachment between the ureter and bladder, with a short flap valve that doesn’t work. In some children an infrequent voiding pattern may cause reflux.

In many cases, reflux appears to be passed down (inherited). About 1 in 3 sisters and brothers of children with reflux also have this health problem. Also, if a mother has been treated for reflux, as many as half of her children may also have reflux.

VUR and Infections

VUR is most often found after a child has a UTI. A urinary tract infection is a bacterial infection of the urinary tract. It may involve the kidney, the bladder or both. In fact, about 1 of every 3 children with a UTI is found to have vesicoureteral reflux.

Some signs of a kidney infection are:

  • fever
  • pain in the belly or lower back
  • feeling ill in general
  • feeling sick to the stomach
  • throwing up

Signs of a bladder infection are:

  • painful and frequent voiding
  • an urgent need to pass urine
  • wetting (lack of urinary control)

The signs of UTIs in babies may not be as clear, but may involve:

  • fever
  • fussiness
  • throwing up
  • diarrhea
  • poor weight gain

Older children can also have UTIs without any clear signs.

The bacteria that cause UTIs are often from the child’s feces. Even with clean habits, bacteria may gather in the groin, and enter the urethra and bladder. If the child has VUR, the bacteria may travel to the kidney(s) and result in infection.

Though VUR is most often found after a child has been treated for a UTI, it is key to remember that VUR by itself does not cause UTI and UTI does not cause reflux.