Clot Retraction Time (F) Flashcards
What is the other term of clot retraction?
It is also called as clot contraction
What are the characteristics of clot retraction?
1) Increased stabilization of fibrin clot involving PLTs and GP IIb/IIIa
2) Fibrin interacts w/ actin-myosin cytoskeleton; this interaction is mediated by GP IIb/IIIa
3) Shrinking of blood clot within blood vessels + shortening of fibrin threads + extruding of excess fluid
What are the purposes of CRT?
1) In-vitro assessment of clot retraction
2) Measures the duration of the clot to retract from the sides of a glass tube
3) Already considered as an obsolete test because results are greatly affected by Hct
What are the mats needed for CRT?
1) Sahli’s pipette
2) Wasserman tube
3) Glass rod
4) Calibrated centrifuge tube
What are the different methodologies of CRT?
1) Hirschboeck method
2) Stefanini method
3) Macfarlane method
Answer the ff questions:
Given method: Hirschboeck method
1) What is the other name?
2) What is the sx used?
3) What is the temp needed for incubation?
4) What are the normal values w/ corresponding interpretations?
1) Castor oil method
2) Capillary blood
3) Not needed
4) a. < 15 mins: shortened
b. 15 - 45 mins: normal
c. > 45 mins: prolonged
* qualitative assessment of clot retraction
What is the procedure (or steps) of Hirschboeck method?
1) Pour castor oil up to 1 in from the rim of the Wassermann tube. Collect sx thru skin puncture
2) Aspirate blood up to 20 mm^3 mark of the Sahli’s pipette
3) Expel the blood into the central surface of the castor oil by touching the tip of the pipette into the oil. Start timer
4) Place the tube on a rack. Record the time when dimpling formation or nipple-like protrusion is already present on the surface of the drop of blood
Answer the ff questions:
Given method: Stefanini method
1) What is the other name?
2) What is the sx used?
3) What is the temp needed for incubation?
4) What are the normal values w/ corresponding interpretations?
1) Test tube method
2) Venous blood
3) At 37 DC
4) C: partial retraction
B: complete retraction
A: no retraction
* qualitative assessment of clot retraction
* retraction should begin after 1 hr and should end within 18 - 24 hrs
What is the procedure (or steps) of Stefanini method?
1) Collect sx thru veni using a syringe. Expel 3 - 5 mL of blood into a Wassermann tube
2) Close the tube w/ a cotton plug. Place the tube on a rack in a H2O bath set at 37 DC
3) Observe for the presence of coagulation after 1, 2, 16, 18, and 24 hrs
4) Rim the clot w/ a stiff straight wire if blood clot adhered to the wall of the tube. Rimming the clot will detach the clot
Answer the ff questions:
Given method: Macfarlane method
1) What is the other name?
2) What is the sx used?
3) What is the temp needed for incubation?
4) What are the normal values w/ corresponding interpretations?
1) None
2) Venous blood
3) At 37 DC
4) a. < 44%: decreased
b. 44% - 67%: normal
c. > 67%: increased
* quantitative assessment of clot retraction
What is the formula of Macfarlane method?
CRT = volume of serum in mL / total volume of blood in mL X 100
What is the procedure (or steps) of Macfarlane method?
1) Collect sx thru veni using a syringe. Expel 5 mL of blood into a calibrated centrifuge tube
2) Immerse a glass rod in the column of blood. Fit a cork to maintain the stability of the glass rod. Place the tube on a rack in a H2O bath set at 37 DC. Start timer
3) Observe for the presence of coagulation at 5 - 10 min interval. After 1 hr, remove tube from the H2O bath
4) Remove the clot by pulling the glass rod from the sx. Record the remaining amt of serum in the tube. Compute for CRT in %
What are the causes of prolonged CRT?
1) PLT-type von Willebrand disease
2) Glanzmann thrombasthenia
3) ALL thrombocytopenia-causing conditions
What are the causes of shortened CRT?
ALL thrombocytosis-causing conditions
