Urine normally flows in one direction down from the kidneys through tubes called ureters, to the bladder. But what happens when there is an abnormal flow of urine from the bladder back into the ureters? About one-third of children with urinary tract infections are found to have vesicoureteral reflux (VUR). The following information should help you better understand this condition.
What happens under normal conditions?
Normally, urine is made by filtration of blood through the kidneys and then urine flows from the kidneys through tubes called ureters in one direction into the bladder. The connection between the ureter and bladder on each side is a one-way "flap valve" that prevents urine from backing up into the kidney. During urination, the bladder muscle tightens and the urethral sphincter relaxes, allowing urine to leave the bladder through another tube called the urethra. This entire system from the kidneys to the urinary opening is called the urinary tract.
What is vesicoureteral reflux (VUR)?
Vesicoureteral reflux (VUR) is the condition in which urine travels backward from the bladder toward the kidney and may affect one or both ureters.
In most children, reflux is a birth defect and is caused by an abnormal attachment between the ureter and bladder with a short, ineffective flap valve. In some children, an infrequent urination pattern may cause reflux to occur.
When the "flap valve" malfunctions and allows urine to flow backward, bacteria from the bladder easily enters the kidney. A child with reflux is more likely to develop a kidney infection (pyelonephritis) that can cause kidney damage. When urine backflow is more severe, the ureters and kidneys become large and distorted. More severe reflux is associated with greater kidney damage in the presence of infection. Although reflux can have these serious medical consequences, it is a "silent" abnormality, that is, reflux does not cause pain, discomfort or problems with urination. Also, generally reflux does not cause kidney damage unless there is a urinary tract infection.
Who gets vesicoureteral reflux (VUR)?
VUR occurs in about 10 percent of healthy children. It is usually diagnosed after a child has a urinary tract infection and sometimes from prenatal findings. The average age at diagnosis of reflux is two to three years but it may be diagnosed at any age, even in newborn babies or older children. Approximately three-quarters of children being treated for reflux are girls.
In many children, reflux appears to be inherited. About one-third of sisters and brothers of children with reflux also have the disorder. In addition, if a mother has been treated for reflux, as many as half of her children may also have reflux.
How is a urinary tract infection related to vesicoureteral reflux (VUR)?
A urinary tract infection (UTI) is a bacterial infection of the urinary tract and may involve the kidney, the bladder or both. A UTI involving the kidney is termed a kidney infection or pyelonephritis. Typical symptoms include fever, pain in the abdomen or lower back, a general ill feeling and/or nausea and vomiting. A UTI that primarily involves the bladder is termed a bladder infection or cystitis. Typical symptoms include painful and frequent urination, an urgent need to urinate and many children experience wetting (lack of urinary control). Newborns with UTIs often do not have such specific symptoms. Instead, their signs may include fever, fussiness, vomiting, diarrhea and poor weight gain. Older children can have UTIs without any obvious symptoms.
The bacteria that cause UTIs are typically from bacteria in the child's own feces. Even with excellent hygiene, bacteria may gather in the genital area (with no external signs of infection) and ultimately enter the urethra and bladder. If the child has reflux, the bacteria may be transported to the kidney(s) and result in kidney infection.
Although reflux usually is diagnosed after a child has been treated for a UTI, it is important to remember that reflux does not cause UTI and UTI does not cause reflux.
How is vesicoureteral reflux (VUR) diagnosed?
Reflux is diagnosed with a test called a voiding cystourethrogram (VCUG), which is an X-ray of the bladder. A thin plastic tube called a catheter is inserted into the urethra. Fluid containing an X-ray dye is injected through the tube until the bladder is full, and then the child is asked to urinate. Pictures of the bladder are taken to see if the dye goes backward up to one or both kidneys. The VCUG usually takes 15 to 20 minutes. In some instances, the test is performed with fluid containing a tiny amount of radioactive tracer and the test is monitored with a special camera. Infection related to using a catheter for these tests occurs in a small proportion of children, so the urologist may recommend that antibiotics be given before and after the procedure.
Ways to ease discomfort and anxiety related to inserting a catheter should be discussed with the doctor. A few children become upset and need to be held during the test. Performing the test using general anesthesia may cause incomplete testing because it is important to observe whether there is reflux when the child is urinating.
If reflux is found, an isotope renal scan may be done to check how well the kidneys are working and to look for kidney damage. In some cases, a kidney and bladder sonogram may be done to check the size of the kidneys.
How is vesicoureteral reflux (VUR) measured?
Reflux can be measured or graded. The doctor looks at an X-ray of the urinary tract to determine the reflux grade. The reflux grade indicates how much urine is flowing back into the ureters and kidneys and helps the doctor decide what type of care is most appropriate.
The most common system of grading reflux - the International Study Classification - includes five grades.
Grade I results in urine reflux in to the ureter only.
Grade II results in urine reflux into the ureter and the renal pelvis, without distention (hydronephrosis).
Grade III results in reflux into the ureter and the renal pelvis, causing mild hydronephrosis.
Grade IV results in moderate hydronephrosis.
Grade V results in severe hydronephrosis and twisting of the ureter.
What are the risks of vesicoureteral reflux (VUR)?
In children with reflux and UTI, kidney damage may occur. Higher grades of reflux are associated with greater risk of kidney damage.
How is vesicoureteral reflux (VUR) treated?
Children with reflux undergo a careful urological history and physical exam to determine the level of risk for developing kidney damage or scarring. Important information includes whether the child is urinating regularly, whether they have normal bladder control during the day, whether they empty the bladder completely, and whether they have constipation. Many children with reflux have what urologist term "dysfunctional elimination syndrome", in which the child urinates infrequently and/or incompletely. These children are at particular risk for kidney infection with reflux. On the other hand, in children with normal bladder control, normal kidneys, and lower grades of efflux, the risk of kidney infection seems low.
The basis for medical treatment is that reflux often will gradually disappear. The average age for this to occur is five to six years. The goal of medical treatment is to prevent UTI and kidney damage while growth and development allow reflux to disappear with time. Reflux improves or disappears in many children because the junction between the bladder and the ureter develops and increases in length as a child grows. The lower the grade of reflux, the more likely it is to disappear.
Medical treatment includes the recommendation to use the restroom regularly and be certain that the child has regular bowel movements; this is termed "bladder training." In many children a low dosage of a preventive antibiotic is prescribed to prevent UTI. On occasion, other medications are recommended if the child is having difficulty with bladder control. The child is seen in the office periodically for a physical examination and the urine is examined for infection. From time to time, the child undergoes X-ray studies of the bladder and/or kidneys to monitor the status of the reflux and growth of the kidneys.
The goal of surgical treatment is to cure reflux with an operation and thus avoid the potential risks of continued reflux. The usual type of surgical therapy is performed under general anesthesia through an incision in the lower abdomen. The operation consists of correcting the flap-valve attachment to the ureter to the bladder to prevent reflux from occurring. No artificial material is used in this procedure and numerous techniques have been proven to be effective. Usually, a catheter is used to drain the bladder for a few days after the operation and the patient is generally in the hospital for several days. After the operation, a follow-up X-ray evaluation is performed several months later to be certain that the operation was successful. Once the reflux is successfully corrected, it is unlikely to recur.
Another type of surgical correction is called endoscopic surgery. The surgeon inserts an instrument called a cystoscope into the urethral opening to see inside the bladder. A substance is then injected into the area where the ureter enters the bladder to try to repair the reflux. This technique requires general anesthesia and usually can be performed as an outpatient procedure but may not have quite the same success rate depending upon the situation.
Frequently asked questions:
Is vesicoureteral reflux contagious?
Can vesicoureteral reflux (VUR) be prevented?
No. VUR cannot be prevented but most infections that result from VUR can be prevented.