Genitourinary Radiology > Kidneys > Parenchymal > Small Kidney > Reflux Nephropathy


Reflux Nephropathy


Also known as chronic atrophic pyelonephritis, relux nephropathy is the result of parenchymal scarring caused by reflux of either sterile or infected urine leads to renal atrophy with an irregular contour. Contour abnormality should be differentiated from fetal lobation.

Reflux that leads to nephropathy must be chronic and is usually massive. Damage usually occurs during childhood, but changes are often not found until adulthood. Children usually present with recurrent urinary tract infections.

Parenchymal atrophy leads to broad-based scarring centered over the underlying calyx, which is clubbed (distorted calyx is called “clubbed”). Reflux through the ducts of Bellini often occurs in areas of compound calyces, which is most common at the poles, leading to selective atrophy in those areas. The midportion of the kidney is often spared, though advanced cases involve the entire kidney.


Gray scale ultrasound of kidney snowing normal upper pole parenchyma (*) which measures greater than 1cm but loss and thinning of lower pole parenchyma (arrows) in patient with chronic reflux disease resulting in lower pole cortical atrophy.

Gray scale ultrasound of kidney snowing marked cortical thinning and irregularity from chronic pyelonephritis resulting in severe cortical loss (arrows).


Contrast enhanced CT scan in patient with chronic reflux disease on right shows marked cortical thinning and irregularity (arrows) similar to the ultrasounds above and contrasted to normal left kidney (LK).


Pathologic specimens in patient with chronic reflux and pyelonephritis shows the so-called "peanut" kidney.  The kidneys are small and scarred with cortical thinning.


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