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Vesicoureteral Reflux

Vesicoureteral reflux occurs when urine washes back (refluxes) from the bladder (vesico), up the ureter (ureteral), and toward the kidney.

There are two types of vesicoureteral reflux: primary and 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 is due to a blockage, often caused by infection, in the urinary tract.

Under normal conditions, urine flow is one-directional (downstream). This means that it flows from the kidneys, down the ureters, into the bladder and then it is voided out the urethra.

The urinary system is made up of:

• Two kidneys on either side of the spine, just below the rib cage.
• Two tubes ("ureters") that carry urine from the kidneys into the bladder.
• The bladder - a muscular structure that expands to store urine.
• A urethra to carry urine out of the body.
• A muscle at the bladder neck ("sphincter") that holds back urine.
• Urine - water and waste products filtered from the blood as it passes through the kidneys.

Normally, the bladder stores urine until it is filled. At that point, nerve fibers in the bladder send a message through the spinal cord to the brain. The brain responds by sending a message back to the bladder, causing it to contract. It also causes the sphincter to relax, allowing urine to pass through the urethra ("voiding").

How Vesicoureteral Reflux Occurs

The ends of the ureters enter the bladder at an angle. They are embedded in the muscle wall of the bladder. This is called "tunneling."

As the bladder fills with urine, its muscle wall stretches and compresses the ends of the ureters. The effect is similar to pinching the end of the straw. This prevents urine from refluxing into the ureter.

If the tunnel portion of the ureter is absent or too short, reflux can result. Reflux can occur in one or both ureters. The condition is usually present at birth and has a tendency to run in families. It is typically detected when a child begins to have urinary tract infections. It can also occur from voiding problems (such as holding or waiting too long) that put more pressure on the bladder.

Grades of Vesicoureteral Reflux

Vesicoureteral reflux is graded according to how far urine washes back into the ureter:

Grade I
Urine washes back into only part of the ureter.

Grade II
Urine fills the entire ureter and the collecting segment of the kidney (pelvis).

Grade III
Urine washes back through the entire ureter to fill the pelvis and stretches these structures.

Grade IV and V
The kidney and ureter are distended with urine. Kidney damage often results.

Detecting Vesicoureteral Reflux

Children who develop urine tract infections should have the following tests:

• Renal Ultrasound
  Uses sound waves to determine the size and shape of the kidneys, ureters, and bladder. The test is not painful and requires no drugs or X-rays. It is very useful, but it is limited and can not tell if there is reflux, nor is it accurate in determining renal damage.
• Voiding Cystourethrogram
  Uses an X-ray to examine the bladder and urethra while the bladder is full and during voiding to determine whether urine refluxes into the ureters. The test requires catheterization of the bladder and the use of a contrast dye. The child is then asked to urinate, allowing visualization of the bladder under pressure. There is a small amount of radiation exposure.
• Renal SPECT Scan (DMSA)
  Determines if infected refluxed urine has damaged the kidney. During the test, a nuclear isotope is injected into a vein and attaches to normal kidney tissue. It is a very safe test, but takes several hours from the shot until the picture can be taken.

Treating Vesicoureteral Reflux

Children with low-grade reflux often outgrow the condition. This is because the length of the "tunnel" of ureter increases as they develop. To keep their urine free of infection and to prevent kidney scarring, these children typically receive a low dosage of antibiotics once a day. We also emphasize voiding frequently and treating any constipation, which will help reduce urinary infections.

Children with higher grades of reflux or evidence of kidney scars might require surgical correction particularly if the reflux persists for several years. During surgery, the ureter is detached from the bladder and then re-attached by tunneling a portion of the ureter through the muscle wall. Tunneling creates a valve that prevents reflux.

Since antibiotic usage is controversial, we have been looking at ways to limit use of antibiotics. This includes stopping them in highly selected cases and consideration of earlier and minimally invasive surgery.

All children with reflux should be re-evaluated each year. Urinary tract infections require prompt treatment. If a child is ill with a fever, a urine culture should be obtained. Signs of a urinary tract infection include:

• Dark, foul-smelling urine
• Frequent trips to the bathroom
• Pants-wetting
• Burning sensation during urination
• Fever or chills
• Vomiting
• A strong, persistent urge to urinate
• Blood in the urine (hematuria) or cloudy, strong-smelling urine
• Fever
• Abdominal or flank pain

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