Reflux nephropathy

Definition

Reflux nephropathy is a condition in which the kidneys are damaged by the backward flow of urine into the kidney.

Alternative Names

Chronic atrophic pyelonephritis; Vesicoureteric reflux; Nephropathy - reflux; Ureteral reflux

Causes, incidence, and risk factors

Urine flows from each kidney, through tubes called ureters, and into the bladder. When the bladder is full, it squeezes and sends the urine out through your urethra. None of the urine should flow back into the ureter when the bladder is squeezing. Each ureter has a one-way valve where it enters the bladder, preventing urine from flowing back up the ureter.

But in some people, the urine flows back up to the kidney. This is called reflux.

Over time, the kidneys may be damaged or scarred by this reflux. This is called reflux nephropathy

Reflux can occur in people whose ureters do not attach properly to the bladder or if the valves do not work well. Children may be born with this problem or other birth defects of the urinary system that cause reflux nephropathy.

Reflux nephropathy can occur with other conditions that lead to a blockage of urine flow, including:

• Bladder outlet obstruction
• Bladder stones
• Neurogenic bladder, which can occur in people with multiple sclerosis

Reflux nephropathy also can occur from swelling of the ureters after a kidney transplant or trauma to the ureter.

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

Symptoms

Some people can have no symptoms from reflux nephropathy. The problem may be found when different tests are done for other reasons.

If symptoms do occur, they might be similar to those of a urinary tract infection, nephrotic syndrome, or chronic kidney failure.

High blood pressure may be the only symptom.

Signs and tests

Reflux nephropathy is often found when a child is checked for repeat or suspicious bladder infections. If reflux is discovered, the child's siblings may also be checked, because reflux can run in families.

The blood pressure may be raised, and there may be signs and symptoms of chronic kidney failure.

Blood and urine tests will be done, and include:

• BUN - blood
• Creatinine - blood
• Creatinine clearance
• Urinalysis or 24-hour urine studies
• Urine culture

Imaging tests that may be done include:

• Abdominal CT scan or ultrasound of the kidneys
• IVP
• Kidney ultrasound
• Radionuclide cystogram
• Voiding cystourethrogram

Treatment

The degree of reflux is separated into five different grades. Simple or mild reflux often falls into grade I or II. How severe the reflux is and how much damage to the kidney is present helps determine treatment.

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

• Antibiotics taken every day to prevent infections
• Careful watching
• Repeated urine cultures
• Yearly ultrasound of the kidneys

Controlling blood pressure is the most important measure to delay kidney damage. Therefore, the doctor may prescribe medicines to control high blood pressure. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) are used.

Surgical therapy is reserved for children who fail medical therapy.

More severe reflux may require surgery, especially in children who do not respond to medical therapy. Surgery to place the ureter(s) back into the bladder can be done to stop reflux nephropathy.

More severe reflux may require surgery, such as the following:

• Ureteral reimplantation
• Reconstructive repair

These surgeries result in less frequent and less severe urinary tract infections.

If needed, patients will be treated for chronic kidney disease.

Expectations (prognosis)

The outcome varies. Most cases of reflux nephropathy get better 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.

Reflux nephropathy may cause kidney failure in children and young adults.

Complications

• Blockage of the ureter after surgery
• Chronic or repeat urinary tract infections
• Chronic renal failure if both kidneys are involved (can progress to end-stage kidney disease)
• Kidney infection
• High blood pressure
• Nephrotic syndrome
• Permanent damage to one or both kidneys
• Persistent reflux
• Scarring of the kidneys

Calling your health care provider

Call your health care provider if you have symptoms of reflux nephropathy, or if you have decreased urine output or other new symptoms.

Prevention

Quickly treating conditions that cause reflux of urine into the kidney may prevent reflux nephropathy.

References

In: Brenner BM, ed. Brenner: Brenner and Rector's the Kidney. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 14.