o Inflammation of the renal parenchyma and renal pelvis due to an infectious source
o Most often secondary to an ascending lower urinary tract infection from gram-negative bacteria
§ E. coli
o Exception is S. aureus, which is spread hematogenously
· Pathologic Causes
o Vesicoureteral reflux
o Obstruction in the collecting system usually due to a calculus
· Signs and symptoms
o Flank pain
o Increased frequency of urination.
o On exam, costovertebral angle tenderness may be present.
· Clinical Findings
§ Elevated white blood cell count.
§ White blood cell casts
o Acute pyelonephritis is clinical diagnosis,
§ Radiographic imaging is used to evaluate underlying pathology
§ Rule out any complications.
o Emphysematous pyelonephritis
§ Most often occurs in diabetics
· Can produce gas in the collecting system and renal parenchyma.
· Radiographic Imaging Findings
o Enlarged kidneys (U/S and CT)
o Hydronephrosis (U/S and CT)
o Wedge shaped areas of low attenuation secondary to decreased perfusion (CT)
o Loss of the ability to distinguish the corticomedullary border (CT)
o Perinephric stranding (CT)
Right kidney is markedly enlarged and
o Antibiotics for non-complicated pyelonephritis.
o Radical nephrectomy for emphysematous pyelonephritis.
o Percutaneous drainage of abscesses
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