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Vesicoureteral reflux (VUR) refers to a condition in which urine flows from the bladder, back up the ureter, and back into the kidneys.
The normal flow of urine begins in the collecting system of each kidney. Urine then flows out of each kidney and into a tube called the ureter. Each ureter leads into the bladder, where the urine collects until it is passed out of the body. Normally, urine should flow only in this direction. In vesicoureteral reflux, however, urine that has already collected in the bladder is able to flow backwards from the bladder, up the ureter, and back into the collecting system of the kidney. VUR may be present in either one or both ureters.
Vesicoureteral reflux causes damage to the kidneys in two ways:
- The kidney is not designed to withstand very much pressure. When VUR is present, back pressure of the urine on the kidney is significant. This can damage the kidney.
- The kidney is usually sterile, meaning that no bacteria are normally present within it. In VUR, bacteria that enter through the urinary tract may be carried back up the ureter with the urine. These bacteria can enter the kidney, causing severe infection.
Causes and symptoms
Most cases of VUR are due to a defect in the way the ureter is implanted into the bladder. The angle may be wrong, or the valve (which should allow urine only one-way entrance into the bladder) may be weak. Structural defects of the urinary system may also cause VUR. These include a situation in which two ureters leave a kidney, instead of the usual one (duplicated ureters), and in which the ureter is greatly enlarged at the end leading into the bladder (ureterocele).
VUR alone does not usually cause symptoms. Symptoms develop when an infection has set in. The usual symptoms of infection include frequent need to urinate, pain or burning with urination, and blood or pus in the urine. Occasionally, VUR is suspected when a child has a difficult time becoming toilet trained. In these cases, the bladder may become irritable and spasm, because it is never totally empty of urine. When the kidneys have been damaged, high blood pressure may develop.
VUR is diagnosed by taking a series of x-ray pictures. These are taken after putting a small tube (catheter) into the bladder. The bladder is then filled with a dye solution which lights up on the x-ray picture. Pictures are taken immediately, followed by x rays taken while the patient is urinating. This will allow reflux to be demonstrated, and will reveal whether the level of reflux increases when pressure increases during urination. Reflux is then graded based on the height and effects of the VUR:
- Grade I. VUR enters just the portion of the ureter closest to the bladder. The ureter appears normal in size.
- Grade II. VUR enters the entire ureter, and goes up into the collecting system of the kidney. The ureter and the collecting system appear normal in size and structure.
- Grade III. VUR enters the entire ureter and kidney collecting system. Either the ureter or the collecting system are abnormal in size or shape.
- Grade IV. Similar to Grade III, but the ureter is greatly enlarged.
- Grade V. Similar to Grade IV, but the ureter is also abnormally twisted/curved, and the collecting system is greatly enlarged, with absence of the usual structural details.
Treatment depends on the grade that is diagnosed. In grades I and II, the usual treatment involves long-term use of a small daily dose of antibiotics to prevent the development of infections. The urine is tested regularly to make sure that no infection occurs. The kidneys are evaluated regularly to make sure that they are growing normally and that no new scarring has occurred. Grade III VUR can be treated with antibiotics and careful monitoring. New infections, scarring, or stunting of kidney growth may result in a need for surgery. Grades IV and V are extremely likely to require surgery.
Surgery for VUR consists of reimplanting the ureters into the bladder at a more normal angle. This usually improves the functioning of the valve leading into the bladder. When structural defects of the urinary system are present, surgery will almost always be required to repair these defects.
Prognosis is dependent on the grade of VUR. About 80% of children with grades I and II VUR simply grow out of the problem. As they grow, the ureter lengthens, changing its angle of entry into the bladder. About 50% of children with grade III VUR will require surgery. Nearly all children with grades IV and V VUR will require surgery. In these cases, it is usually best to perform surgery at a relatively young age, in order to avoid damage and scarring to the kidneys.
While there is no known method of preventing VUR, it is important to note that a high number of the siblings of children with VUR will also have VUR. Many of these siblings (about 36%) will have no symptoms, but will be discovered through routine examinations prompted by their brother's or sister's problems. It is important to identify these children, so that antibiotic treatment can be used to prevent the development of infection and kidney damage.
American Foundation for Urologic Disease. 300 West Pratt St., Suite 401, Baltimore, MD 21201. (800) 242-2383.
Bladder — The muscular sac which receives urine from the kidneys, stores it, and ultimately works to remove it from the body during urination.
Reflux — A condition in which flow is backwards from normal.
Ureter — A muscular tube leading from the kidney to the bladder, down which the urine flows.
esophageal reflux (gastroesophageal reflux) reflux of the stomach contents into the esophagus.
hepatojugular reflux distention of the jugular vein induced by applying manual pressure over the liver; it suggests insufficiency of the right heart.
intrarenal reflux reflux of urine into the renal parenchyma.
vesicoureteral reflux (vesicoureteric reflux) backward flow of urine from the bladder into a ureter.
ves·i·co·u·re·ter·al re·flux[MIM*314550, MIM*193000]
backward flow of urine from bladder into ureter.
Etymology: L, vesica + Gk, oureter, ureter; L, refluxus, backflow
an abnormal backflow of urine from the bladder to the ureter, resulting from a congenital defect, obstruction of the outlet of the bladder, or edema or scarring secondary to infection of the lower urinary tract. Reflux increases the hydrostatic pressure in the ureters and kidneys and may cause permanent damage. The condition is characterized by abdominal or flank pain, enuresis, pyuria, hematuria, proteinuria, and bacteriuria accompanied by persistent or recurrent urinary tract infections. Diagnosis is made by cystoscopy and voiding cystourethrography. Obstruction of the ureter or defective implantation of the ureter in the bladder may be surgically corrected. Antibacterial medication, urinary tract antiseptics, and analgesia are usually prescribed for any infection that causes or results from this condition.
ves·i·co·u·re·ter·al re·flux(ves'i-kō-yŭr-ē'tĕr-ăl rē'flŭks)
Backward flow of urine from bladder into ureter.