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:
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").
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.
Vesicoureteral reflux is graded according to how far urine washes back into the ureter:
Urine washes back into only part of the ureter.
Urine fills the entire ureter and the collecting segment of the kidney (pelvis).
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.
Children who develop urine tract infections should have the following tests:
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: