ASCP Clinical Microscopy

Question 1

In a urinalysis, what does a positive reagent strip (dipstick) result for leukocyte esterase indicate?

Accepted Answer

The presence of white blood cells (neutrophils) or their breakdown products

Answer

Leukocyte esterase is an enzyme found in neutrophil granules. A positive dipstick result indicates WBCs (pyuria) or lysed neutrophils. It is a screening test for urinary tract infection but requires microscopic confirmation.

Question 2

Which urinary casts are characteristic of acute tubular necrosis (ATN)?

Accepted Answer

Granular (muddy brown) casts

Answer

Granular muddy brown casts in urine are characteristic of acute tubular necrosis. They form from degenerating tubular epithelial cells and cellular debris in the renal tubular lumen, creating the coarsely granular appearance.

Question 3

Which stain is used to identify fat/lipid in urine sediment?

Accepted Answer

Oil Red O or Sudan III stain

Answer

Oil Red O (and Sudan III/IV) are lipophilic dyes that stain neutral fats (triglycerides and cholesterol esters) orange-red. They are used to confirm lipiduria (oval fat bodies, fatty casts) in nephrotic syndrome or tubular injury.

Question 4

A WBC cast in urine sediment is most indicative of:

Accepted Answer

Pyelonephritis or acute interstitial nephritis

Answer

WBC (leukocyte) casts indicate that inflammation is occurring within the renal tubules and parenchyma, characteristic of pyelonephritis (bacterial) or acute interstitial nephritis (drug-induced or autoimmune). They must be distinguished from clumped WBCs not in cast matrix.

Question 5

Spermatozoa seen on a urine microscopy report in a female patient most likely indicates:

Accepted Answer

Specimen contamination from recent sexual intercourse or vesico-vaginal communication

Answer

Spermatozoa in female urine almost always represent contamination from recent sexual intercourse (retrograde into bladder, vaginal contamination of midstream specimen, or very rarely from vesico-vaginal fistula). They have no diagnostic significance for urinary tract disease.

ASCP Practice Test

ASCP Practice Test

ASCP Clinical Microscopy