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Kidney Infection (cont.)

Kidney Infection Diagnosis

The most important test in diagnosing kidney infection is a urinalysis (UA). This is basically a test to analyze urine sample and evaluate for an infection in the urine. Urinalysis is done by collecting a clean catch, midstream urine in a sterile collection cup. The urine may be analyzed by the doctor in the office using or by analysis in a laboratory.

Because urine is normally sterile, any finding suggesting an infection may be considered abnormal and supportive of a kidney infection.

  • Gross inspection of urine (macroscopic analysis) may reveal cloudy urine.
  • With a dipstick urine test, typical findings consistent with urinary tract infection include positivity for leukocyte esterase, nitrates, or blood.
  • In microscopic urinalysis (analysis under the microscope), the presence of white blood cells, red blood cells, or bacteria in the urine is highly suggestive of a kidney infection. Generally, visualization of 100,000 bacteria in one cc of a urine sample supports the diagnosis of urinary tract infection or kidney infection.
  • In some situations, less than 100,000 bacteria may still be enough to make the diagnosis. If no white blood cells or bacteria are seen in the urine, then another diagnosis may need to be considered.
  • When bacteria are recovered from urine, they need to be further analyzed to determine the exact type of bacteria. Once the exact type of bacteria is known, usually its sensitivity to typical antibiotics is also tested to further guide of treatment.
  • In more complicated cases, imaging studies, such as a CT scan of the abdomen and pelvis, or an abdominal ultrasound, may also be necessary. Complicated kidney infections are usually associated with more severe symptoms and with more significant involvement of the kidneys including an abscess or gas formation in the kidney which can be detected by CT scan or ultrasound.
  • Recurrent or long-standing (chronic) kidney infections sometimes result from kidney stones or other structural abnormalities, such as an enlarged prostate or long-standing reflux of urine in the ureters (vesico-ureteral reflux). X-rays, ultrasounds, or CT scans may be necessary to investigate these cases.
Medically Reviewed by a Doctor on 12/29/2015

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Read What Your Physician is Reading on Medscape

Pyelonephritis, Acute »

Acute pyelonephritis is a potentially organ- and/or life-threatening infection that characteristically causes some scarring of the kidney with each infection and may lead to significant damage to the kidney (any given episode), kidney failure, abscess formation (eg, nephric, perinephric), sepsis, or sepsis syndrome/shock/multiorgan system failure.

Read More on Medscape Reference »

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