(See also Overview of Kidney Filtering Disorders.)
Reflux nephropathy is kidney scarring caused by urine flowing backward from the bladder into a ureter and toward a kidney.
Normally, where the bladder and the ureter join, the ureter tunnels slightly sideways through the bladder wall. The muscles of the bladder wall help keep the end of the ureter shut so that urine flows in only one direction—from the ureter into the bladder. Some people are born with abnormalities of the junction between the ureter and bladder that allow the urine to flow backward during urination—from the bladder into the ureters. This condition is called vesicoureteral reflux (VUR). It can occur in one or both ureters. The backward flow of urine makes urinary tract infections (UTIs) more likely to develop and to cause kidney inflammation and scarring, a condition called reflux nephropathy.
About 30 to 45% of children and about 1% of newborns who have a UTI that causes a fever have VUR. VUR is less common among blacks and sometimes tends to run in families. Children usually outgrow VUR by about age 5 years.
VUR causes no symptoms, but children with VUR tend to have repeated UTIs. Reflux nephropathy cause no symptoms. Occasionally, children with reflux nephropathy develop chronic kidney disease, sometimes during adolescence.
Doctors suspect VUR in the following children:
Doctors sometimes also suspect VUR in children with close relatives who have the disorder and in children or adults who have repeated UTIs and in whom imaging tests show kidney scarring.
Doctors may suspect that a fetus has VUR if routine prenatal ultrasonography shows a swollen kidney (called hydronephrosis).
When they suspect VUR, doctors may do imaging tests to look for abnormalities of the kidneys and ureters that can cause VUR as well as any kidney damage that may have resulted. These tests may include ultrasonography, voiding cystourethrography, and radionuclide cystourethrography. If VUR has resolved but resulted in scarring, the scarring may be visible on the imaging tests.
Children with VUR and their parents should be aware of the symptoms of UTI, which can vary by age. They may include fever, vomiting, burning during urination, and inability to control the bladder. If reflux is moderate or severe, children may need to take antibiotics to prevent UTIs. However, it is not clear that taking antibiotics prevents kidney damage.
Sometimes, children with severe VUR are treated with surgical procedures designed to strengthen the tissues around the ureter's opening into the bladder and thus prevent backflow of urine into the ureters.