Acute Pyelonephritis
Submitted by Matthew Krasner, M.D. 

 

·        Etiology

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

§         Klebsiella

§         Proteus

§         Pseudomonas. 

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       Fever

o       Chills

o       Flank pain

o       Dysuria

o       Increased frequency of urination.

o       On exam, costovertebral angle tenderness may be present.

 

·        Clinical Findings

o       CBC

§         Elevated white blood cell count.

o       Urinalysis

§         Bacteriuria

§         Pyuria

§         White blood cell casts

o       Acute pyelonephritis is clinical diagnosis,

§         Radiographic imaging is used to evaluate underlying pathology

§         Rule out any complications.

 

·        Complications

o       Abscess

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
has a wedge-shaped area of low attenuation

 

·        Treatment

o       Antibiotics for non-complicated pyelonephritis.

o       Radical nephrectomy for emphysematous pyelonephritis.

o       Percutaneous drainage of abscesses