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 valve-like mechanisms between the ureters and bladder 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 that 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 keep 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

Reflux nephropathy may not produce any obvious signs. Reflux is often discovered when a child with repeat or suspect bladder infections is evaluated radiologically. If reflux is discovered the child's siblings may also be evaluated, because reflux can run in families.

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

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

Reflux nephropathy occurs in about 4 out of 1,000 asymptomatic individuals. However, in infants and children who experience urinary tract infections, its prevalence approaches 40% to 50%. Reflux nephropathy may lead to chronic renal failure and end-stage renal disease. The symptoms may not be present if only one kidney is affected or may be those of urinary tract infections, nephrotic syndrome, or chronic renal 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

• 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

• 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