Hema Lec #3: Laboratory Assessment of Platelets Flashcards
A decreased count of a normal range of platelet
thrombocytopenia
A increased count of a normal range of platelet
thrombocytosis
What is comminly used method for direct platelet count
Brecker-cronkite method
What solution is diluted in the blood that completely hemolyzed RBC
1% Ammonium oxalate
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
c. is requires the use of phase contrast microscope and special phase hemocytometer
What dilution is diluted into a solution if the patient is severely thrombocytopenic? Mention also the pipette used
1:20. wbc pipette
A source of error that commonly seen in blood taken from difficult extractions. What is the remedy for this error?
Platelet Clumping. Re-draw
A source of error that platelets are appear to almost entirely encircle the neutrophils
Platelet satellitism.
What causes then plateles encircles the neutrophils?
EDTA is used as an anticoagulant
What solution is used to give remedy when platelets encircle neutrophils?
sodium citrate
What source of error is refer when there is falsely low plt count, falsely high RBC count especially with machines using impedance principle?
Giant platelet
most common source of error (accdg to Dr. Baisac)
incorrect dilution
What method is most commonly employed ways of determining platelet quantity?
Automated Methods
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
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
What methods is used when a suspennsion of cells or particles is aspirated into a channel surrounmded by a narrow fluid system
flow cytometry
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
false.
forward angle = size of the cell
size scatter = internal complexity
It is used for estimation and cross-checking for both manual anf automated counts
Peripheral Blood Smear
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
b. It is an accurate cell count
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
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
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?
Ivy method
It is similar to Ivy Method and most used method nowadays
Surgicutt Method
Other bleeding time method that uses earlobe/fingertip as site of incision
Duke’s method
Gross screening test of platelet quantity and function, as well as fibrinolysis
Clot retraction time
T/F. Clot retraction reflects the number and quantity of platelets, fibrinogen concentration, fibrinolytic activity, and packed red cell volume
False. QUALITY
