2 URINE MICROSCOPY AND CLINICAL CORRELATIONS Flashcards
Which of the following dyes are used to make Sternheimer-Malbin stain?
A. Hematoxylin and eosin
B. Crystal violet and safranin
C. Methylene blue and eosin
D. Methylene blue and safranin
B. Crystal violet and safranin
The Sternheimer-Malbin stain is a supravital stain used to differentiate renal tubular epithelium from transitional cells and PMNs. The mononuclear cells are clearly distinguished from both live and dead PMNs. Transitional cells have pale blue cytoplasm, but renal cells take up both dyes, resulting in an azurophilic appearance (orange-purple cytoplasm and dark purple nucleus).
Which of the following statements regarding WBCs in urinary sediment is true?
A. “Glitter cells” seen in urinary sediment are a sign of renal disease
B. Bacteriuria in the absence of WBCs indicates lower urinary tract infection (UTI)
C. WBCs other than PMNs are not found in urinary sediment
D. WBC casts indicate that pyuria is of renal, rather than lower urinary, origin
D. WBC casts indicate that pyuria is of renal, rather than lower urinary, origin
The majority of WBCs in urinary sediment will be PMNs. Eosinophils and
mononuclear WBCs will occasionally be seen. High numbers of eosinophils often indicate an allergic drug reaction, causing inflammation in the medullary interstitium and tubules. Mononuclear cells are especially likely in patients with chronic inflammatory diseases and in renal transplant rejection, where they may account for as many as 30% of the WBCs. Glitter cells are PMNs with highly refractile granules
exhibiting Brownian movement. They are seen only when the urine SG is below 1.020. These cells resist staining with the Sternheimer-Malbin stain and are considered to be living (fresh) WBCs. When seen in large numbers, they indicate urinary tract injury (with pseudopod extensions, they point to infection). The presence of bacteria in urine in the absence of PMNs usually results from contamination by vaginal or skin flora that multiply in vitro, especially in unrefrigerated specimens. The presence of WBC casts is always significant and, when associated with pyuria and bacteriuria, indicates renal involvement in the infection.
Which description of urinary sediment with the Sternheimer-Malbin stain is correct?
A. Transitional epithelium: cytoplasm pale blue, nucleus dark blue
B. Renal epithelium: cytoplasm light blue, nucleus dark purple
C. Glitter cells: cytoplasm dark blue, nucleus dark purple
D. Squamous epithelium: cytoplasm pink, nucleus pale blue
A. Transitional epithelium: cytoplasm pale blue, nucleus dark blue
After staining with the Sternheimer-Malbin stain, transitional epithelium are readily differentiated from renal tubular cells and WBCs because their cytoplasm is pale blue. Live WBCs exclude the Sternheimer-Malbin stain, whereas dead cells stain with a deeply blue-purple nucleus and pale orange-blue cytoplasm. Renal epithelium have an orange-purple cytoplasm and dark purple nucleus. Squamous epithelium have a blue or purple cytoplasm and an orange-purple nucleus. Red cells stain very pale pink or not at all and hyaline casts stain faintly pink.
SITUATION: A 5-mL urine specimen is submitted for routine urinalysis and is
analyzed immediately. The SG of the sample is 1.012, and the pH is 6.5. The dry reagent strip blood test result is a large positive (3+), and the microscopic examination shows 11 to 20 RBCs/HPF. The leukocyte esterase reaction is a small positive (1+), and the microscopic examination shows 0 to 2 WBCs/HPF. What is the most likely cause of these
results?
A. Myoglobin is present in the sample
B. Free hemoglobin is present
C. Insufficient volume is causing microscopic results to be underestimated
D. Some WBCs have been misidentified as RBCs
C. Insufficient volume is causing microscopic results to be underestimated
Given the SG and pH, most RBCs and WBCs will be intact. Both the RBC and WBC counts are lower than expected from the dry reagent strip test results. Myoglobin or free hemoglobin may account for the poor correlation between the blood reaction and the RBC count, but this does not explain the lower than expected WBC count. Microscopic reference ranges are based on concentrating a uniform volume of sediment from 12 mL of urine. When less urine is used, falsely low results will be obtained unless corrective action is taken. The specimen should be diluted with normal saline to 12 mL, then centrifuged at 450 × g for 5 minutes. Urinary sediment should be prepared according to the established procedure and the results multiplied by the dilution factor (in this case, 12 ÷ 5, or 2.4).
Which of the following statements regarding epithelial cells in the urinary system is
correct?
A. Caudate epithelial cells originate from the upper urethra
B. Transitional cells originate from the upper urethra, ureters, bladder, or renal pelvis
C. Cells from the proximal renal tubule are usually round
D. Squamous epithelium line the vagina, urethra, and wall of the urinary bladder
B. Transitional cells originate from the upper urethra, ureters, bladder, or renal pelvis
Caudate cells are transitional epithelium that have a sawtooth-shaped tail and are found in the urinary bladder and the pelvis of the kidney. Transitional epithelia line the upper two thirds of the urethra and the ureters as well as the urinary bladder and renal pelvis. Renal tubular cells may be columnar, polyhedral, or oval, depending on the portion of the tubule from which they originate. Cells from the proximal tubule are columnar and have a distinctive brush border. Squamous epithelia line the vagina and lower third of the urethra.
Which of the statements regarding examination of unstained urinary sediment is true?
A. Renal cells can be differentiated reliably from WBCs
B. Large numbers of transitional cells are often seen after catheterization
C. Neoplastic cells from the bladder are not found in urinary sediment
D. RBCs are easily differentiated from nonbudding yeast
B. Large numbers of transitional cells are often seen after catheterization
Renal cells and PMNs are about the same size and can be confused in unstained sediment. Catheterization often releases large clumps or sheets of transitional and squamous cells. These should be distinguished from neoplastic cells derived from the urinary bladder. When cells appear atypical (e.g., large cells in metaphase), they should be referred to a pathologist for cytological examination. Nonbudding yeast cells
are approximately the same in size and appearance as RBCs. When RBCs are reported in the absence of a positive blood test, the probability of an error in microscopy is high. The microscopic examination should be reviewed for the presence of yeast.
Which of the following statements regarding cells found in urinary sediment is true?
A. Transitional cells resist swelling in hypotonic urine
B. Renal tubular cells are often polyhedral and have an eccentric round nucleus
C. Trichomonads have an oval shape with a prominent nucleus and a single anterior
flagellum
D. Clumps of bacteria are frequently mistaken for blood casts
B. Renal tubular cells are often polyhedral and have an eccentric round nucleus
Transitional epithelial cells readily take up H2O and appear much larger than renal cells or WBCs when urine is hypotonic. Transitional cells are considered a normal component of the sediment unless present in large numbers and associated with signs of inflammation, such as mucus and PMNs, or presenting features of malignant cells. In contrast, renal cells are significant when seen conclusively in the sediment. They are often teardrop-shaped, polyhedral, or elongated cells with a round eccentric nucleus. Conclusive identification requires staining. T. vaginalis displays an indistinct nucleus and two pairs of prominent anterior flagella. Amorphous urate crystals deposited on the slide may be mistaken for granular or blood casts.
Which of the following statements regarding RBCs in the urinary sediment is true?
A. Yeast cells will lyse in dilute acetic acid but RBCs will not
B. RBCs are often swollen in hypertonic urine
C. RBCs of glomerular origin often appear dysmorphic
D. Yeast cells will tumble when the cover glass is touched, but RBCs will not
C. RBCs of glomerular origin often appear dysmorphic
RBCs are difficult to distinguish from nonbudding yeast in unstained sediment. RBCs tumble when the cover glass is touched and will lyse when the sediment is reconstituted in normal saline containing 2% volume per volume (v/v) acetic acid. A nonhemolyzed trace blood reaction confirms the presence of RBCs. RBCs have a granular appearance in hypertonic urine as a result of crenation. The RBC membrane becomes distorted when passing through the glomerulus, often appearing scalloped,
serrated, or invaginated. Such cells are called dysmorphic RBCs and are associated with glomerulonephritis.
Renal tubular epithelial cells are shed into urine in largest numbers in which condition?
A. Malignant renal disease
B. Acute glomerulonephritis
C. Nephrotic syndrome
D. Cytomegalovirus (CMV) infection of the kidney
D. Cytomegalovirus (CMV) infection of the kidney
Although seen in glomerulonephritis and pyelonephritis, the largest numbers of renal tubular cells appear in urine in association with viral infections of the kidney. Renal epithelium may show characteristic viral inclusions associated with CMV and rubella. High numbers of renal epithelium are also found in the sediment of patients with drug-induced tubular nephrosis and in some cases of heavy metal poisoning. Renal tumors do not usually shed cells into urine.
The ova of which parasite is likely be found in the urinary sediment?
A. Trichomonas vaginalis
B. Entamoeba histolytica
C. Schistosoma hematobium
D. Trichuris trichiura
C. Schistosoma hematobium
Ova of S. hematobium are most often recovered from urine because the adult trematodes colonize the blood vessels of the urinary bladder. The eggs are approximately 150 × 60 µm in size and are nonoperculated. They are yellowish and have a prominent terminal spine.
Oval fat bodies are often seen in:
A. Chronic glomerulonephritis
B. Nephrotic syndrome
C. Acute tubular nephrosis
D. Renal failure of any cause
B. Nephrotic syndrome
Oval fat bodies are degenerated renal tubular epithelia that have reabsorbed cholesterol from the filtrate. Although they can occur in any inflammatory disease of the tubules, they are commonly seen in nephrotic syndrome, which is characterized by marked proteinuria and hyperlipidemia.
