Fast Five Quiz: Are You Prepared to Confront Pyelonephritis?

Vecihi Batuman, MD


February 26, 2018

Scintigraphy with technetium-99m dimercaptosuccinic acid is almost as sensitive clinically as contrast-enhanced helical/spiral CT (CECT) in detecting focal renal abnormalities during acute pyelonephritis in adults. This modality is not used much in adults, however, because the findings are not specific; focal abnormalities may indicate abscess, cyst, infarct, pyelonephritis, or tumor. In children, technetium-99m dimercaptosuccinic acid scintigraphy is the preferred study because it involves less radiation exposure than CT scans. It is excellent for helping detect inflammation, scarring, and the distribution of renal function between kidneys.

CECT scanning is the imaging study of choice in adults with acute pyelonephritis. CECT is more sensitive than ultrasonography and intravenous pyelography (which has only 25% sensitivity), and it can more readily identify alterations in renal parenchymal perfusion, alterations in contrast excretion, perinephric fluid, and nonrenal disease.

When properly collected, a clean-catch specimen adequately reflects the microbiology of the urine in the bladder. This technique can be performed by ambulatory females aged 6 years and older who do not have any limiting physical handicap. Clean-catch technique can also be performed by ambulatory males aged 6 years and older who do not have any limiting physical handicap. Specimens are usually reliable. Catheterization poses a small risk of introducing bacteria into the normally sterile bladder environment. Circumstances that justify this risk when a urine culture is necessary include the following:

  • Inability to void or difficulty voiding urine even with hydration

  • Marked obesity or redundant labia in females

  • Ill patients who cannot reliably perform the procedure

  • Performance of a urologic procedure during which a specimen can be collected

  • Children 2-6 years of age (if a clinician-assisted clean-catch specimen cannot be collected)

Pyuria is defined as more than 5-10 white blood cells (WBCs) per high-power field (hpf) on a specimen spun at 2000 revolutions/min for 5 minutes. Almost all patients with pyelonephritis have significant pyuria (>20 WBCs/hpf), although the numbers may be smaller, particularly in those with subacute pyelonephritis.

For more on the workup of acute pyelonephritis, read here.


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