Overview
In reflux nephropathy, Hodson initially noted the association of vesicoureteral reflux (VUR) with renal parenchymal scarring. Such scarring is demonstrated in the images below.
Sonogram in a child with recurrent urinary tract infections and vesicoureteral reflux. Focal contour indentation along the lower lateral margin of the left kidney (longitudinal view) reflects a focal pyelonephritic scar, which is an appearance distinct from the more global parenchymal scarring seen in the next image.
Longitudinal sonogram of the left kidney in an 18-year-old woman with a history of recurrent urinary tract infections demonstrates normal parenchymal thickness in the upper portion of the kidney and generalized marked parenchymal thinning in the lower portion. The latter reflects chronic pyelonephritic scarring secondary to urinary tract infection and vesicoureteral reflux that occurred in childhood.
Renal ultrasonography (RUS) and voiding cystourethrography (VCUG) are the preferred radiologic examination methods.
The 2 procedures provide complementary information. RUS helps in evaluating the upper urinary tract (kidneys and proximal portion of the collecting system) for anomalies, masses, calcification, hydronephrosis, and size and can identify renal scarring if moderate to severe in degree. VCUG helps in evaluating for VUR and the anatomy of the lower urinary tract (bladder and urethra).
Nuclear medicine renal scanning with a cortical imaging agent (eg, technetium-99m [99m Tc] dimercaptosuccinic acid) is a better means of detecting and identifying renal scarring than is ultrasonography.
Imaging with renal scanning may require sedation in younger children. Sedation is increasingly requested, although rarely necessary, for children undergoing VCUG.
Magnetic resonance imaging (MRI) is not routinely indicated in the evaluation of reflux nephropathy because of the procedure’s cost and the potential need for patient sedation. As with CT scanning, MRI can demonstrate renal scarring and hydronephrosis, but not VUR.
Computed tomography (CT) scanning is not indicated in the evaluation of reflux nephropathy because of radiation dose, the need for intravenously administered contrast material, and the potential need for patient sedation. Although CT scans can demonstrate renal scarring and hydronephrosis, they cannot demonstrate VUR.