Vesicoureteral Reflux

Vesicoureteral reflux (VUR) is a condition where pee (urine) flows in the wrong direction. Instead of flowing from your kidneys, down into your ureters and bladder where it stays until you pee, your pee flows backward from your bladder.

Your urinary tract is typically a one-way valve, with pee flowing down your urinary tract. This valve-like mechanism prevents pee from going back up into your ureters after it gets to your bladder. Typically, pee should flow like this:

• Kidneys produce pee. Typically, you have two kidneys.
• Two thin, muscular tubes called ureters carry pee from your kidneys to your bladder.
• Your bladder holds or stores your pee. It can expand like a balloon.
• Your pee leaves your body through your urethra. Your urethra is the opening your pee comes out of.

In VUR, pee flows back — or refluxes — from your bladder into one or both of your ureters and, in some cases, to one or both kidneys. It happens most often due to an issue that prevents the one-way valve from functioning as it should.

Vesicoureteral reflux (VUR) mostly affects newborns, infants and young children ages 2 and under, but older children and (rarely) adults can also have VUR.

Pee flowing the wrong way can cause bacteria to get into your child’s kidneys and cause infection. Kidney infections can cause permanent kidney damage when left untreated.

Treatment for VUR depends on the severity of your child’s symptoms, age and other factors. Mild cases may not need treatment and some children outgrow VUR. But some children need surgery or medication to treat VUR so it doesn’t cause kidney damage.

What are the types of vesicoureteral reflux?

VUR that affects only one ureter and kidney is called unilateral reflux. VUR that affects both ureters and kidneys is called a bilateral reflux.

The two types of VUR are primary and secondary:

• Primary VUR: Most cases of VUR are primary and more commonly affect only one ureter and one kidney (unilateral reflux). With primary VUR, your child is born with a ureter that doesn’t connect into their bladder properly. The flap valve between their ureter and bladder wall doesn’t close correctly, so pee refluxes from their bladder to the ureter and, in some cases, their kidney.
• Secondary VUR: Secondary VUR occurs when a blockage in the urinary tract causes an increase in pressure and pushes pee back up from the urethra into your child’s bladder, ureters or kidneys. The blockage could result from an abnormal fold of tissue in the urethra that keeps pee from flowing freely out of your child’s bladder. Another cause of secondary VUR might be a problem with nerves that can’t stimulate the bladder to release pee. Children with secondary VUR often have bilateral reflux (affects both ureters or both kidneys).

What are the stages of vesicoureteral reflux (VUR)?

The stages of VUR are grades and there are five of them. Five is the most severe form of VUR and one is the mildest form. The grading system is based on:

• How far the pee backs up into the urinary tract.
• The width of the ureter(s) or if the ureter is enlarged.

The grade breakdown is:

• Grade one: Pee goes backward up into a ureter, but the ureter is a normal width.
• Grade two: Pee backs up into a ureter and the kidney pelvis, which is the area where the ureter and kidney meet. Both the kidney pelvis and ureter haven’t gotten wider.
• Grade three: The ureter(s), kidney pelvis and calyces (where pee collection begins in the bladder) are mild to moderately enlarged due to pee backing up.
• Grade four: The ureter(s) are curved and moderately widened, and the kidney pelvis and calyces are also moderately widened because of too much pee backing up.
• Grade five: The ureter(s) are extremely distorted and enlarged. The kidney pelvis and calyces are very large from an excessive amount of pee backing up.

How common is vesicoureteral reflux (VUR)?

About 1% to 3% of children have vesicoureteral reflux (VUR). About 75% of children with VUR are assigned female at birth (AFAB).