HEMA 1 (Hemostasis Test) Flashcards
What are the factors to consider in hemostasis test?
- Temp
- Hemolysis
- Glass surface
- Tissue thromboplastin
What are the effects of temp in hemostasis?
- Room temp = labile factors (V, VIII) will deteriorate for an extended period of time
- Cold temp = activates factor VII and XI
What is the effect of hemolysis in hemostasis?
Hemolyzed RBCs act like tissue thromboplastin in activating plasma clotting factors
What are the effects of glass surface in hemostasis?
- The contact factors (HMWK, PK, XII, XI) will be activated prematurely by contact w/ glass
- Recommended materials are:
a. Plastic
b. Polystrene
c. Silicone-coated glass
What is the effect of tissue thromboplastin in hemostasis?
Potent clot-activating substance found in fluids that escape from injured cells and tissue spaces
What are the technical errors that can cause hemolysis?
- Excessive stains through prolonged application of the tourniquet (> 1 min)
- Moisture / contamination in the needle, syringe, / bld container
- Using needle w/ too small a bore (20 G: most commonly used)
- Frothing of sx due to entry of air
- Expelling bld from the syringe through the needle
- Excessive and vigorous mixing of bld w/ the anticoagulant
What is the color of EDTA?
Lavender top
What are the fxns of EDTA?
- Prevents coagulation by chelating Ca
- For bld cell ct (RBC, WBC, PLT)
What is the bld to anticoagulant (B:AC) ratio of EDTA?
4:1
What is the color of 3.2% sodium citrate?
Light blue top
What are the fxns of 3.2% Na citrate?
- For coagulation test
- Preserves the labile clotting factors V and VIII better
*What is the sp content of 3.2% Na citrate?
0.109 M Na citrate
What is the B:AC ratio of 3.2% Na citrate?
9:1
What are the uses of citrated bld?
- Aggregation studies
- Coagulation studies
What is the sx used for aggregation studies and how is this sx obtained?
PRP
Centri @ 60 - 100 g for 30 mins
What is the sx used for coagulation studies and how is this sx obtained?
PRP
Centri @ 2,000 - 2,300 g for 10 - 15 mins
What are the anticoagulants used in PLT ct?
- EDTA
- 3.2% Na citrate
When to use 3.2% Na citrate as anticoagulant in PLT ct?
Can be used when PLT satellitism occurs
What must be done to PLT ct if 3.2% Na citrate is used as anticoagulant?
PLT ct is multiplied by 1.1
What is the counting chamber used in PLT ct?
Neubauer counting chamber
What is the pipet used in PLT ct?
RBC Thoma pipet
What is the dilution used in PLT ct?
1:100 / 1:200
What must be the characteristic of diluting fluid used in PLT ct?
Must preserve PLT integrity while inhibiting their aggregation
What are the methods that can be used in PLT ct?
- Tocantin’s method
- Brecker-Cronkite method
What is the diluting fluid used in Tocantin’s method?
Rees-Ecker
What is the stain used in Tocantin’s method?
Brilliant cresyl blue (BCB)
What is the formula (per uL) used for Tocantin’s method?
Total PLTs cted X 200 (dilution) X 10 (depth correction) / 1 (area correction)
What microscopy is used in Brecker-Cronkite method?
Phase-contrast microscopy method