Specimen Integrity and Preservatives

Question 1

Urine specimen should be tested within

Answer 1

2 hours

Question 2

Ideally, urine should be tested within

Answer 2

30 mins

Question 3

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

Answer 3

As the urine is voided

Question 4

Usual cause of changes in unpreserved urine

Answer 4

Bacteria

Question 5

Increased parameters in urine being unpreserved (pBAON)

Answer 5

pH, Bacteria, Odor, Nitrite

Question 6

Odor and pH usually change due to

Answer 6

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

Question 7

Bacteria and nitrite increase due to

Answer 7

Bacterial multiplication

Question 8

Color of urine in unpreserved specimen

Answer 8

Darkened or modified due to oxidation or reduction of metabolites

Question 9

Urobilin in unpreserved specimen

Answer 9

Increased due to oxidation

Question 10

Decreased parameters in unpreserved urine

Answer 10

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

Question 11

Least affected parameter in urine

Answer 11

Protein

Question 12

Clarity decreases due to

Answer 12

Bacterial multiplication; precipitates amorphous material

Question 13

Glucose decreases due to

Answer 13

Glycolysis

Question 14

Ketones decrease due to

Answer 14

Volatilization and bacterial metabolism

Question 15

Bilirubin decreases due to

Answer 15

Photo-oxidation, light exposure to biliverdin

Question 16

Urobilinogen decreases due to

Answer 16

Oxidation to urobilin

Question 17

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

Answer 17

Disintegrate in dilute alkaline urine

Question 18

Trichomonas in unpreserved urine would

Answer 18

Lose motility; possible misidentification as WBCs

Question 19

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

Answer 19

Does not exist

Question 20

How are preservatives chosen for urine?

Answer 20

Best suits the needs of the required analysis

Question 21

Advantages of refrigeration

Answer 21

Does not interfere with chemical tests

Question 22

Disadvantages of refrigeration of urine

Answer 22

Raises SG by hydrometer; precipitates amorphous phosphates and urates

Question 23

Preservative of choice for routine UA and urine culture

Answer 23

Refrigeration (prevents bacterial growth for 24 hrs)

Question 24

Advantages of thymol in urine

Answer 24

Preserves glucose and sediments well

Question 25

Disadvantages of thymol for urine

Answer 25

Interferes with acid precipitation test for protein

Question 26

Advantages of boric acid

Answer 26

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

Question 27

Disadvantages of boric acid

Answer 27

Precipitates crystals when used in large amounts

Question 28

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

Answer 28

Boric acid

Question 29

Excellent sediment preservative for urine

Answer 29

Formalin (Formaldehyde)

Question 30

Disadvantage of using formalin

Answer 30

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

Question 31

Preservative of choice for Addis Count

Answer 31

Formalin (Formaldehyde)

Question 32

Specimen container washed with formalin helps in

Answer 32

Preserving cells and casts

Question 33

Advantages of toluene (toluol) and phenol

Answer 33

Does not interfere with routine tests

Question 34

Disadvantage of toluene (toluol)

Answer 34

Floats on urine surface; clings to pipettes and testing material

Question 35

Best all-around preservative (Turgeon)

Answer 35

Toluene (toluol)

Question 36

Prevents glycolysis and good preservative for drug analysis

Answer 36

Sodium fluoride

Question 37

Disadvantage of sodium fluoride

Answer 37

Inhibits reagent strip tests for glucose, blood, and leukocytes

Question 38

Alternative to sodium fluoride for reagent strip testing

Answer 38

Sodium benzoate

Question 39

Disadvantage of phenol

Answer 39

Causes an odor change

Question 40

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

Answer 40

1 drop/ounce of specimen

Question 41

Advantage of commercial preservative tablets

Answer 41

Convenient when refrigeration is not possible; controlled concentration minimizes interference

Question 42

Disadvantage of commercial preservative tablets

Answer 42

May contain one or more preservatives such as sodium fluoride

Question 43

To minimize interference in urine analysis, commercial preservative tablets should

Answer 43

Be checked for their composition to determine possible effects

Question 44

Advantage of urine collection kits

Answer 44

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

Question 45

Advantage of gray C&S tube

Answer 45

Sample stable at room temperature for 48 hrs; preserves bacteria

Question 46

Preservative of gray C&S tube

Answer 46

Boric acid (may not be used for UA)

Question 47

Advantages of yellow plain UA tube

Answer 47

Used on automated instruments

Question 48

Disadvantage of yellow plain UA tube

Answer 48

Must be refrigerated within 2 hours

Question 49

Appearance of yellow plain UA tube

Answer 49

Round or conical bottom

Question 50

Advantage of cherry red/yellow top tube

Answer 50

Stable for 72 hours at room temp; instrument compatible

Question 51

Disadvantage of cherry red/yellow top tube

Answer 51

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

Question 52

Preservative and appearance of cherry red/yellow top tube

Answer 52

Sodium propionate; conical bottom

Question 53

Saccomano fixative composition

Answer 53

50% ethanol and 2% carbowax

Question 54

Fixative for urine cytology

Answer 54

Saccomano fixative

Question 55

Amount of urine for cytology studies using saccomano fixative

Answer 55

50 mL