Pyelonephritis

Diagnosis

  • Catheterization of the ureters and renal pelvis for urinalysis and culture (unnecessarily invasive)
  • Routine urinalysis
  • Bacterial antibodies (false positives)
  • The Fairley bladder washout test
  • Radiographic methods include:
    • Excretory urography
    • Tc-99m DMSA or glucoheptonate nuclear renal scans
    • Voiding cystourethrography
  • Renal biopsy with bacterial culture (not condemned due to excessive risk to the patient)
  • Pediatric patient: should be studied with voiding cystourethrography and nuclear renal scanning to evaluate for vesicoureteral reflux and renal scarring/dysfunction, respectively.
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  • Acute pyelonephritis: usually diagnosed on clinical grounds
  • Chronic pyelonephritis: diagnosed by radiologic and pathologic means
    • CT scanning or ultrasonography to search for predisposing risk factors

Clinical Characteristics

  • Fever, flank pain, costovertebral angle (CVA) tenderness, and infected urine
  • Clinical presentation may vary from acute sepsis to cystitis with mild flank pain
  • Systemic malaise, nausea, and vomiting
  • Lower urinary tract symptoms of dysuria, increased urinary frequency
  • History of previous lower urinary tract infections
  • Severe cases may cause sepsis, hypotension, and death in a compromised host
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  • Acute pyelonephritis: can be self-limited. Multiple bouts can lead to progressive loss of tubules, thereby impairing renal concentrating ability. This is followed by glomerular damage late in the course (chronic pyelonephritis), producing azotemia and hypertension
  • Chronic pyelonephritis: history of recurrent urinary tract infections, may be asymptomatic, radiologically or secondary to complications of chronic azotemia

Special Case: XANTHOGRANULOMATOUS PYELONEPHRITIS (XGP)

Diagnosis

  • The usual symptoms of pyelonephritis
  • Nonfunction of the affected kidney and the process is invariably unilateral
  • Radiologic imaging; reveals renal calculi and a renal mass
  • Perirenal fat may be involved with adjacent subcapsular inflammatory response
  • Bacteriology; Proteus and E. coli
  • The presence of large, often branched calculi in the presence of a renal mass associated with either focal or global renal nonfunction

Complications

Renal Abscess
May follow insufficient treatment of focal bacterial nephritis (lobar nephronia).

Diagnosis:

  • CT, ultrasound, and needle aspiration

Perinephric Abscess

Diagnosis:

  • Similar diagnosis for renal abscess

Emphysematous Pyelonephritis

Diagnosis:

  • Intrarenal parenchymal gas defined by plain x-ray, CT scan, or ultrasound.

References


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