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AUBF > Specimen Integrity and Preservatives > Flashcards

Specimen Integrity and Preservatives Flashcards

1
Q

Urine specimen should be tested within

A

2 hours

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2
Q

Ideally, urine should be tested within

A

30 mins

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3
Q

Physical, chemical, and microscopic characteristics of urine begin to change

A

As the urine is voided

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4
Q

Usual cause of changes in unpreserved urine

A

Bacteria

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5
Q

Increased parameters in urine being unpreserved (pBAON)

A

pH, Bacteria, Odor, Nitrite

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6
Q

Odor and pH usually change due to

A

Urease-producing bacteria that produce ammonia (pH loses CO2)

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7
Q

Bacteria and nitrite increase due to

A

Bacterial multiplication

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8
Q

Color of urine in unpreserved specimen

A

Darkened or modified due to oxidation or reduction of metabolites

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9
Q

Urobilin in unpreserved specimen

A

Increased due to oxidation

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10
Q

Decreased parameters in unpreserved urine

A

Clarity, Glucose, Ketones, Bilirubin, Urobilinogen, RBCs, WBCs, Casts, Trichomonas

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11
Q

Least affected parameter in urine

A

Protein

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12
Q

Clarity decreases due to

A

Bacterial multiplication; precipitates amorphous material

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13
Q

Glucose decreases due to

A

Glycolysis

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14
Q

Ketones decrease due to

A

Volatilization and bacterial metabolism

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15
Q

Bilirubin decreases due to

A

Photo-oxidation, light exposure to biliverdin

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16
Q

Urobilinogen decreases due to

A

Oxidation to urobilin

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17
Q

What happens to RBCs, WBCs, and Casts in unpreserved urine?

A

Disintegrate in dilute alkaline urine

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18
Q

Trichomonas in unpreserved urine would

A

Lose motility; possible misidentification as WBCs

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19
Q

Ideal preservative (bactericidal, inhibit urease, preserve elements, no interference)

A

Does not exist

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20
Q

How are preservatives chosen for urine?

A

Best suits the needs of the required analysis

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21
Q

Advantages of refrigeration

A

Does not interfere with chemical tests

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22
Q

Disadvantages of refrigeration of urine

A

Raises SG by hydrometer; precipitates amorphous phosphates and urates

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23
Q

Preservative of choice for routine UA and urine culture

A

Refrigeration (prevents bacterial growth for 24 hrs)

24
Q

Advantages of thymol in urine

A

Preserves glucose and sediments well

25
Q

Disadvantages of thymol for urine

A

Interferes with acid precipitation test for protein

26
Q

Advantages of boric acid

A

Preserves protein and does not interfere with routine analysis other than pH

27
Q

Disadvantages of boric acid

A

Precipitates crystals when used in large amounts

28
Q

Preservative that keeps pH at 6.0; bacteriostatic at 18 g/dL; for culture transport and C&S; interferes with drug and hormone analyses

A

Boric acid

29
Q

Excellent sediment preservative for urine

A

Formalin (Formaldehyde)

30
Q

Disadvantage of using formalin

A

Reducing agent that interferes with chemical tests for glucose, blood, leukocytes, and copper reduction

31
Q

Preservative of choice for Addis Count

A

Formalin (Formaldehyde)

32
Q

Specimen container washed with formalin helps in

A

Preserving cells and casts

33
Q

Advantages of toluene (toluol) and phenol

A

Does not interfere with routine tests

34
Q

Disadvantage of toluene (toluol)

A

Floats on urine surface; clings to pipettes and testing material

35
Q

Best all-around preservative (Turgeon)

A

Toluene (toluol)

36
Q

Prevents glycolysis and good preservative for drug analysis

A

Sodium fluoride

37
Q

Disadvantage of sodium fluoride

A

Inhibits reagent strip tests for glucose, blood, and leukocytes

38
Q

Alternative to sodium fluoride for reagent strip testing

A

Sodium benzoate

39
Q

Disadvantage of phenol

A

Causes an odor change

40
Q

How many ounces of specimen should be used for phenol preservative?

A

1 drop/ounce of specimen

41
Q

Advantage of commercial preservative tablets

A

Convenient when refrigeration is not possible; controlled concentration minimizes interference

42
Q

Disadvantage of commercial preservative tablets

A

May contain one or more preservatives such as sodium fluoride

43
Q

To minimize interference in urine analysis, commercial preservative tablets should

A

Be checked for their composition to determine possible effects

44
Q

Advantage of urine collection kits

A

Contains collection cup, C&S, preservative tube, or UA tube

45
Q

Advantage of gray C&S tube

A

Sample stable at room temperature for 48 hrs; preserves bacteria

46
Q

Preservative of gray C&S tube

A

Boric acid (may not be used for UA)

47
Q

Advantages of yellow plain UA tube

A

Used on automated instruments

48
Q

Disadvantage of yellow plain UA tube

A

Must be refrigerated within 2 hours

49
Q

Appearance of yellow plain UA tube

A

Round or conical bottom

50
Q

Advantage of cherry red/yellow top tube

A

Stable for 72 hours at room temp; instrument compatible

51
Q

Disadvantage of cherry red/yellow top tube

A

Bilirubin and urobilinogen decrease if exposed to light and left at room temp

52
Q

Preservative and appearance of cherry red/yellow top tube

A

Sodium propionate; conical bottom

53
Q

Saccomano fixative composition

A

50% ethanol and 2% carbowax

54
Q

Fixative for urine cytology

A

Saccomano fixative

55
Q

Amount of urine for cytology studies using saccomano fixative

AUBF (26 decks)

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