Hema Lec #3: Laboratory Assessment of Platelets

Question 1

A decreased count of a normal range of platelet

Answer 1

thrombocytopenia

Question 2

A increased count of a normal range of platelet

Answer 2

thrombocytosis

Question 3

What is comminly used method for direct platelet count

Answer 3

Brecker-cronkite method

Question 4

What solution is diluted in the blood that completely hemolyzed RBC

Answer 4

1% Ammonium oxalate

Question 5

Which of the following is true about Manual platelet counting:

a. Whole blood is diluted with sodium citrate
b. Capillary blood is preffered even if venous blood is available
c. is requires the use of phase contrast microscope and special phase hemocytometer
d. it must be performed within 4 hours of the time that the specimen is collected; w/in 24 hrs if the spx is refrigerated

Answer 5

c. is requires the use of phase contrast microscope and special phase hemocytometer

Question 6

What dilution is diluted into a solution if the patient is severely thrombocytopenic? Mention also the pipette used

Answer 6

1:20. wbc pipette

Question 7

A source of error that commonly seen in blood taken from difficult extractions. What is the remedy for this error?

Answer 7

Platelet Clumping. Re-draw

Question 8

A source of error that platelets are appear to almost entirely encircle the neutrophils

Answer 8

Platelet satellitism.

Question 9

What causes then plateles encircles the neutrophils?

Answer 9

EDTA is used as an anticoagulant

Question 10

What solution is used to give remedy when platelets encircle neutrophils?

Answer 10

sodium citrate

Question 11

What source of error is refer when there is falsely low plt count, falsely high RBC count especially with machines using impedance principle?

Answer 11

Giant platelet

Question 12

most common source of error (accdg to Dr. Baisac)

Answer 12

incorrect dilution

Question 13

What method is most commonly employed ways of determining platelet quantity?

Answer 13

Automated Methods

Question 14

Which of the following is true about Electrical Impedance?

a. It uses coulter principle
b. each cell that passes through alters the electrical impedance and are differentiated based on the size
c. the giant latelets’ large gize can be mistaken as RBC and WBC causing low plt count
d. A suspension of cells or particles is aspirated into a channel surrounded by a narrow fluid system

Answer 14

a. It uses coulter principle
b. each cell that passes through alters the electrical impedance and are differentiated based on the size
c. the giant latelets’ large gize can be mistaken as RBC and WBC causing low plt count

Question 15

What methods is used when a suspennsion of cells or particles is aspirated into a channel surrounmded by a narrow fluid system

Answer 15

flow cytometry

Question 16

T/F. the light is either scatterd or absorbed at certain angles when it strikes a certain cells.

forward angle= internal complexity
side scatter = size of the cell

Answer 16

false.
forward angle = size of the cell
size scatter = internal complexity

Question 17

It is used for estimation and cross-checking for both manual anf automated counts

Answer 17

Peripheral Blood Smear

Question 18

All but one are not refer to peripheral smear evaluation:

a. it provides a rapid estimate of platelet numbers
b. It is an accurate cell count
c. Examine isat least 10 different Oil immersion field for platelet estimation
d. The estimation of platelets from blood smear does not replace actual quantitative measurement

Answer 18

b. It is an accurate cell count

Question 19

All of the following are true about Bleeding Time EXCEPT:

a. in vivo measurement of platelet adhesion of locally injured vascular subendothelium
b. provides an estimate of the integrity of the platelet plug and thereby measures the interaction between veins and platelet
c. reflects platelet function by timing the length of time two standardized puncutres of the ventral arm near the wrist
d. a blood pressure cuff is inflated to about 30 mmHg

Answer 19

b. provides an estimate of the integrity of the platelet plug and thereby measures the interaction between veins and platelet
c. reflects platelet function by timing the length of time two standardized puncutres of the ventral arm near the wrist
d. a blood pressure cuff is inflated to about 30 mmHg

Question 20

What Bleeding time metohd is used when if reflects platelet functuon by timing the length of time two standardized punctures of the ventral forearm stop bleeding while a blood pressure cuff inflated to 40 mm Hg and place it on the upper arm?

Answer 20

Ivy method

Question 21

It is similar to Ivy Method and most used method nowadays

Answer 21

Surgicutt Method

Question 22

Other bleeding time method that uses earlobe/fingertip as site of incision

Answer 22

Duke’s method

Question 23

Gross screening test of platelet quantity and function, as well as fibrinolysis

Answer 23

Clot retraction time

Question 24

T/F. Clot retraction reflects the number and quantity of platelets, fibrinogen concentration, fibrinolytic activity, and packed red cell volume

Answer 24

False. QUALITY

Question 25

T/F. Degree of clot retraction is inversely proportional to number of platelet and directly proportional to the hematocrit and level of fibrinogen.

Answer 25

FALSE. directly proportional to number of platelet and inversely proportional to hematocrit and level of fibrinogen

Question 26

What specimen is used for clot retreaction time?

Answer 26

non-anticoagulated blood blood

Question 27

Measuring the capability of the platelets to aggregate

Answer 27

Platelet Aggregometry

Question 28

T/F. Platelet-poor plasma treated with a known aggregating agent is used in platelet aggregometry.

Answer 28

False. Platelet-rich Plasma

Question 29

Which is not true about Platelet Aggregometry?

a. it also monitors antiplatelet drug therapy
b. performd on a turbidimetric aggregometer
c. aggregmeter serves as an standardized spectrophotometer
d. none of the above

Answer 29

d. none of the above

Question 30

All but one are not true about Antiplatelet Antibody Assay

a. routinely done especially in obstetric patients or previously pregnant patient
b. techniques include complement fixation assay, lysis of chromium 51-labelled platelets,
c. platelet refractoriness
d. seen in plasma of patients in autoimmune conditions like ITP

Answer 30

a. routinely done especially in obstetric patients or previously pregnant patient