Pediatric Acute Pyelonephritis

  • Etiology: Ascending urinary tract infection or hematogenous infection
  • Imaging US: Focal spherical hyperechoic swelling
  • Imaging US Color Doppler: Hypoperfused
  • Imaging US Power: Hypoperfused
  • Imaging CT: Kidney may be enlarged with perinephric stranding and have peripheral wedge shaped areas that show striated nephrogram of heterogeneously striated decreased enhancement
  • DDX: Renal tumor which will not resolve on antibiotics
  • Complications: Focus of infection can progress to renal abscess, renal scarring (chronic pyelonephritis
  • Treatment: Antibiotics
  • Clinical:
    — Present with urinary tract infection
    — When the diagnosis of a “mass” (lobar nephronia) is made get a followup US in 1 month to ensure the “mass” has resolved

Radiology Cases of Acute Pyelonephritis

Radiology Cases of Left Acute Pyelonephritis

CT of acute pyelonephritis
Immediate (above) and delayed (below) axial CT with contrast of the abdomen shows multiple low density wedge-shaped lesions in the left kidney and a striated nephrogram on the delayed images.

Radiology Cases of Right Acute Pyelonephritis

CT of acute pyelonephritis
Coronal (above) and axial (below) CT with contrast of the abdomen shows three peripheral wedge shaped areas of low density in the middle and lower right kidney.
US of duplicated kidney with ectopic ureterocele and hydroureteropyonephrosis
Sagittal US of the right kidney (upper left) shows a duplicated renal collecting system with the upper pole replaced by a round structure filled with echogenic material. Sagittal US of the right upper pole ureter (upper right) shows a tortuous ureter filled with echogenic material. Transverse US of the bladder (lower left) shows a round structure in the right side of the bladder that has echogenic material in its inferior portion and anechoic material in its superior portion. Sagittal US of the right ureter and bladder (lower right) shows the tortuous right ureter filled with echogenic material on the left side of the image and the rounded structure with the fluid-fluid level in the right side of the bladder.
US of acute pyelonephritis / acute lobar nephronia
Sagittal US of the right kidney (above) shows an ill-defined hypoechoic mass in the right upper pole that is obscuring the normal outline of the echogenic fat in the renal hilum. The mass was hypoperfused on color and power doppler US. AP image from a voiding cystourethrogram (below) shows bilateral vesicoureteral reflux, grade II on the left and grade III on the right

Radiology Cases of Left Sided Acute Pyelonephritis and Right Sided Chronic Pyelonephritis

CT of acute pyelonephritis and chronic pyelonephritis
Coronal (above) and axial (below) CT with contrast of the abdomen shows multiple peripheral wedge-shaped areas of low density in the upper and middle left kidney. The right kidney is noted to be significantly smaller in size than the left kidney.

Radiology Cases of Left Sided Acute Pyelonephritis and Left Sided Chronic Pyelonephritis

CT of acute pyelonephritis and chronic pyelonephritis in the same kidney
Axial CT with contrast of the abdomen (above) shows the left kidney to have a striated nephrogram appearance with multiple wedge-shaped areas of low density in the left kidney. Coronal CT (below) shows the low density areas are in the upper pole of the left kidney. The lower pole of the left kidney is shrunken and scarred.