Urine flows from the kidneys, through the ureters, and into the bladder. Each ureter has a one-way valve where it enters the bladder, preventing urine from flowing back up the ureter.

Reflux nephropathy occurs when these valves fail, allowing urine to flow back up to the kidney. If the bladder is infected or the urine contains bacteria, the kidney is exposed to the possibility of infection (pyelonephritis ).

Because the pressure in the bladder is generally higher than in the kidney, the reflux of urine exposes the kidney to unusually high pressure. Over time, this increased pressure will damage the kidney and cause scarring.

Reflux may occur in people whose ureters do not extend very far into the bladder. The ureters enter the bladder through "tunnels" in the bladder wall, and the pressure in the bladder normally keeps these tunnels pressed closed. If the bladder-wall tunnels are short or absent, pressure within the bladder can force urine back up the ureter.

Reflux may be associated with other conditions including the following:

• Bladder infections (cystitis)
• Bladder stones
• Bladder outlet obstruction
• Neurogenic bladder
• Abnormal ureters

In some cases, reflux nephropathy produces no symptoms. It is often discovered when a child is evaulated for repeat or suspicious bladder infections. If reflux is discovered, the child's siblings may also be evaluated, because reflux can run in families.

The degree of reflux -- separated into five different grades -- helps determine how the condition is treated. Simple, uncomplicated reflux often falls into grade I or II.

Reflux nephropathy may also occur from temporary swelling that occurs after reimplantation of the ureters during a kidney transplant or because of trauma to the ureter.

About 4 out of 1,000 people with no symptoms have reflux nephropathy, while up to 50% of�infants and children with urinary tract infections have it. Reflux nephropathy may lead to chronic kidney failure and end-stage renal (kidney)�disease.

There may be no�symptoms if only one kidney is affected or symptoms may be those of a urinary tract infection,� nephrotic syndrome, or chronic kindey failure.

The risk factors include a personal or family history of reflux, congenital abnormalities of the urinary tract, and recurrent urinary tract infections.

• Repeated urinary tract infections in a female
• A single urinary tract infection in a male
• Flank pain, back pain, or abdominal pain
• Urinary frequency/urgency increased
• Need to urinate at night
• Burning or stinging with urination
• Feeling of incomplete emptying of the bladder
• Blood in the urine
• Dark or foamy urine

• Urinary hesitancy
• Nausea and vomiting
• Nail abnormalities
• Fever
• Chills

The blood pressure may be elevated, and there may be signs and symptoms of chronic renal failure.

Other tests include:

• Kidney ultrasound
• Serum BUN
• Serum creatinine
• Creatinine clearance
• Urinalysis or 24-hour urine studies that show elevated urine protein levels
• Urine culture that shows infection.
• Radionuclide cystogram may show vesicoureteric reflux or hydronephrosis (distention of the kidney from fluid accumulation in the renal pelvis)
• IVP that shows hydronephrosis, a small kidney, or scarring of the kidney
• Abdominal CT scan or ultrasound of the kidneys or abdomen that shows hydronephrosis, reflux, a small kidney, or scarring.
• A voiding cystourethrogram (VCUG) definitively diagnoses vesicoureteric reflux

Simple, uncomplicated reflux (called primary reflux) less than Grade III may be treated by the following:

• Careful watching
• Repeated urine cultures
• Antibiotics to prevent infection
• Annual ultrasound of kidneys to follow development

• Ureteral reimplantation
• Reconstructive repair

The outcome varies. Most cases of reflux nephropathy resolve on their own. However, the damage to the kidney may be permanent. If only one kidney is involved, the other kidney may continue to function adequately.

Reflux nephropathy may cause as many as 20% of the cases of renal failure in children and young adults.

• Permanent damage to one or both kidneys
• Chronic renal failure if both kidneys are involved (may progress to end-stage renal disease)
• Chronic or recurrent urinary tract infection
• Nephrotic syndrome
• Hypertension
• Pyelonephritis
• Renal scarring
• Persistent reflux
• Obstruction of the ureter following surgery

Call your health care provider if symptoms indicate reflux nephropathy may be present.

Call your health care provider if decreased urine output or other new symptoms develop.

Surgical reimplantation of the ureter(s) into the bladder may be performed to stop reflux nephropathy. This diminishes the frequency and severity of urinary tract infections.

The prompt treatment of conditions that cause reflux of urine into the kidney may prevent reflux nephropathy from developing.