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Get the facts. And the help you need.

Vesicoureteral Reflux (VUR)

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?

No.

Can vesicoureteral reflux (VUR) be prevented?

No. VUR cannot be prevented but most infections that result from VUR can be prevented.

Reviewed: January 2011

Last updated: April 2013

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Vesicoureteral Reflux (VUR) Glossary
  • abdomen: Also referred to as the belly. It is the part of the body that contains all of the internal structures between the chest and the pelvis.

  • abnormality: A variation from a normal structure or function of the body.

  • anesthesia: Loss of sensation in any part of the body induced by a numbing or paralyzing agent. Often used during surgery to put a person to sleep.

  • antibiotic: Drug that kills bacteria or prevents them from multiplying.

  • anxiety: A feeling of apprehension, often characterized by feelings of stress.

  • bacteria: Single-celled microorganisms that can exist independently (free-living) or dependently upon another organism for life (parasite). They can cause infection and are usually treated with antibiotics.

  • bacterial: Of or pertaining to a bacteria.

  • bladder: The bladder is a thick muscular balloon-shaped pouch in which urine is stored before being discharged through the urethra.

  • bladder control: The ability to control the timing of urination. Also referred to as continence.

  • bladder infection: Also known as cystitis. Urinary tract infection involving the bladder. Typical symptoms include burning with urination, frequency, urgency and wetting.

  • bladder training: A behavioral technique that teaches the patient to urinate on a regular schedule and to empty the bladder completely.

  • bowel: Another word for intestines or colon.

  • bowel movement: The act of passing feces (stool) through the anus.

  • catheter: A thin tube that is inserted through the urethra into the bladder to allow urine to drain or for performance of a procedure or test, such as insertion of a substance during a bladder X-ray.

  • constipation: A condition in which a person has difficulty eliminating solid waste from the body and the feces are hard and dry.

  • cyst: An abnormal sac containing gas, fluid or a semisolid material. Cysts may form in kidneys or other parts of the body.

  • cystitis : Inflammation of the bladder, causing pain and a burning feeling in the pelvis or urethra.

  • cystitis: Also known as bladder infection. Urinary tract infection involving the bladder, which causes inflammation of the bladder and results in pain and a burning feeling in the pelvis or urethra.

  • cystoscope: A narrow, tube-like instrument fitted with lenses and a light passed through the urethra to look inside the bladder. The procedure is called cystoscopy (sis-TAW-skuh-pee).

  • cystourethrogram: Also called a voiding cystogram. A specific X-ray that examines the urinary tract. A catheter (hollows tube) is placed in the urethra (tube that drains urine from the bladder to the outside of the body)and the bladder is filled with a liquid dye. X-ray images are taken as the bladder fills and empties. The X-rays will show if there is any reverse flow of urine into the ureters and kidneys.

  • diagnosis: The process by which a doctor determines what disease or condition a patient has by studying the patient's symptoms and medical history, and analyzing any tests performed (e.g., blood tets, urine tests, brain scans, etc.).

  • endoscopic: A procedure performed in order to examine the bladder.

  • feces: The body's solid waste matter, composed of undigested food, bacteria, water and bile pigments, and discharged from the intestines (bowel) through the anus.

  • gene: The basic unit capable of transmitting characteristics from one generation to the next.

  • general anesthesia: Person is put to sleep with muscle relaxation and no pain sensation over the entire body.

  • hydronephrosis: Swelling at the top of the ureter usually because something is blocking the urine from flowing into or out of the bladder.

  • hydronephrosis: Swelling of the top of the ureter, usually because something is blocking the urine from flowing into or out of the bladder.

  • hydronephrosis: Swelling at the top of the ureter, usually because something is blocking the urine from flowing into or out of the bladder.

  • incision: Surgical cut for entering the body to perform an operation.

  • infection: A condition resulting from the presence of bacteria or other microorganisms.

  • ions: Electrically charged atoms.

  • isotope renal scan: An examination that uses small amounts of radioactive materials to measure the function of the kidneys.

  • IV: Also referred to as intravenous. Existing or occurring inside a vein.

  • kidney: One of two bean-shaped organs that filter wastes from the blood and discharge these waste products in urine. The kidneys are located on either side at the level of the 12th ribs toward the back. The kidneys send urine to the bladder through tubes called ureters.

  • kidney infection: Also called pyelonephritis. Urinary tract infection involving the kidney. Typical symptoms include abdominal or back pain, fever, malaise and nausea or vomiting.

  • kidneys: One of two bean-shaped organs that filter wastes from the blood and discharge these waste products in urine. The kidneys are located on either side at the level of the 12th ribs toward the back. The kidneys send urine to the bladder through tubes called ureters.

  • nephritis: Inflammation of the kidneys.

  • pelvis: The bowl-shaped bone that supports the spine and holds up the digestive, urinary and reproductive organs. The legs connect to the body at the pelvis.

  • prenatal: Before birth.

  • pyelonephritis: Also referred to as kidney infection usually caused by a germ that has traveled up through the urethra, bladder and ureters from outside the body. Typical symptoms include abdominal or back pain, fever, malaise and nausea or vomiting.

  • radioactive: Relating to or making use of radioactive substances or the radiation they emit.

  • radioactive tracer: Substances used in nuclear medicine.

  • reflux: Backward flow of urine. Also referred to as vesicoureteral reflux (VUR). An abnormal condition in which urine backs up from the bladder into the ureters and occasionally into the kidneys, raising the risk of infection.

  • reflux: Backward flow.

  • reflux grade: Severity of the reflux.

  • renal: Pertaining to the kidneys.

  • renal pelvis: The basin into which the urine formed by the kidneys is excreted before it travels to the ureters and bladder.

  • renal scan: A nuclear medicine examination that uses small amounts of radioactive materials to measure the function of the kidneys.

  • sonogram: Also referred to as a ultrasound. A technique that bounces painless sound waves off organs to create an image of their structure to detect abnormalities.

  • sphincter: A round muscle that opens and closes to let fluid or other matter pass into or out of an organ. Sphincter muscles keep the bladder closed until it is time to urinate.

  • stent: With regard to treating ureteral stones, a tube inserted through the urethra and bladder and into the ureter. Stents are used to aid treatment in various ways, such as preventing stone fragments from blocking the flow of urine.

  • torted: Twisted.

  • ureter: One of two tubes that carry urine from the kidneys to the bladder.

  • ureteral: Pertaining to the ureter. Also referred to as ureteric.

  • ureters: Pair of tubes that carry urine from each kidney to the bladder.

  • ureters: Tubes that carry urine from the kidneys to the bladder.

  • urethra: A tube that carries urine from the bladder to the outside of the body. In males, the urethra serves as the channel through which semen is ejaculated and it extends from the bladder to the tip of the penis. In females, the urethra is much shorter than in males.

  • urethral: Relating to the urethra, the tube tha carries urine from the bladder to outside the body.

  • urge: Strong desire to urinate.

  • urinary: Relating to urine.

  • urinary tract: The system that takes wastes from the blood and carries them out of the body in the form of urine. Passageway from the kidneys to the ureters, bladder and urethra.

  • urinary tract infection: Also referred to as UTI. An illness caused by harmful bacteria, viruses or yeast growing in the urinary tract.

  • urinate: To release urine from the bladder to the outside. Also referred to as void.

  • urination: The passing of urine.

  • urine: Liquid waste product filtered from the blood by the kidneys, stored in the bladder and expelled from the body through the urethra by the act of urinating (voiding). About 96 percent of which is water and the rest waste products.

  • urologist: A doctor who specializes in diseases of the male and female urinary systems and the male reproductive system. Click here to learn more about urologists. (Download the free Acrobat reader.)

  • UTI: Also referred to as urinary tract infection. An illness caused by harmful bacteria growing in the urinary tract.

  • vas: Also referred to as vas deferens. The cordlike structure that carries sperm from the testicle to the urethra.

  • VCUG: Also referred to as voiding cystourethrogram or voiding cystogram. A catheter is placed in the urethra and the bladder is filled with a contrast dye. X-ray images are taken as the bladder fills and empties to show any blockage or reverse urine flow.

  • vesicoureteral reflux: Also referred to as VUR. An abnormal condition in which urine backs up from the bladder into the ureters and occasionally into the kidneys, raising the risk of infection.

  • void: To urinate, empty the bladder.

  • voiding: Urinating.

  • voiding cystourethrogram: Also referred to as VCUG or voiding cystogram. A specific X-ray that examines the urinary tract. A catheter (hollows tube) is placed in the urethra (tube that drains urine from the bladder to the outside of the body)and the bladder is filled with a liquid dye. X-ray images are taken as the bladder fills and empties. The X-rays will show if there is any reverse flow of urine into the ureters and kidneys.

  • VUR: Also referred to as vesicoureteral reflux. An abnormal condition in which urine backs up into the ureters and occasionally into the kidneys, raising the risk of infection.

Vesicoureteral Reflux (VUR) Anatomical Drawings

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