Chronic Pyelonephritis Workup
- Author: James W Lohr, MD; Chief Editor: Vecihi Batuman, MD, FACP, FASN more...
Imaging Studies
Findings from an intravenous urogram help to establish the diagnosis of pyelonephritis, because they reveal caliceal dilatation and blunting with cortical scars. Ureteral dilatation and reduced renal size also may be evident.
Voiding cystourethrogram (VCUG) findings may document the reflux of urine to the renal pelvis and ureteral dilatation in children with gross reflux.[12]
Radioisotopic scanning with technetium dimercaptosuccinic acid is more sensitive than intravenous pyelography for helping to detect renal scars. This is the preferred test for many pediatric nephrologists and radiologists, because it is sensitive and easy to perform.
Cystoscopy findings show evidence of previous reflux at the ureteral orifices, even if voiding cystourethrogram (VCUG) images show no reflux because of the spontaneous cessation of reflux due to puberty.
Computed tomography (CT) scanning is the procedure of choice to help diagnose XPN.[10] Renal ultrasonographic images may show calculi, but ultrasonography is not a sensitive screening procedure for reflux nephropathy. However, many cases of VUR are suggested based on prenatal ultrasonographic findings.
Approach Considerations
The characteristic renal scars of VUR are often present at the time of the initial diagnosis of chronic pyelonephritis. New renal scars may develop in 3-5% of patients after the initial evaluation. The progression of renal scars is inversely related to the promptness with which specific antibiotic therapy is instituted. The presence of new scars often suggests the occurrence of breakthrough infections.
Urinalysis results may reveal pyuria. Obtain a urine culture, which often isolates gram-negative bacteria, such as Escherichia coli or Proteus species. A negative result from urine culture does not exclude a diagnosis of chronic pyelonephritis. Proteinuria may be present and is a negative prognostic factor for this chronic pyelonephritis. Serum creatinine and blood urine nitrogen levels are elevated (azotemia).
Renal biopsy specimens show focal glomerulosclerosis in advanced reflux nephropathy, while XPN must be distinguished from renal malakoplakia based on the presence of inclusions called Michaelis-Gutmann bodies in the latter.
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