(M) Lesson 6: Platelet Count and Function Test (Part 2) Flashcards
- One of the most traditional tests used in the 1900s
- Ordered by physicians prior to surgery
- Useful to assess bleeding tendency of patient
- When a patient is subjected to certain procedures, some patients have prolonged results
Bleeding Time
- The interval required for the blood to stop flowing from a skin lesion
- Assesses the primary hemostasis
Bleeding Time
To determine the bleeding time, we need what type of incision?
Skin incision
Measures the ability of platelets to adhere to the endothelium
Bleeding Time
What is the primary purpose of bleeding time tests?
Measures/assesses primary hemostasis
Match the following.
- Primary Hemostasis
- Secondary Hemostasis
A. Platelet and Blood Vessels
B. Coagulation Factors/Clotting Factors
- A
- B
What are the different materials needed in assessing bleeding time?
- Lancet
- Filter Paper
- Cotton Balls
- 70% Alcohol
- Stopwatch
- Sphygmomanometer
Match the following.
- Preferred over the ordinary type because it can make a better incision and guarantee more sufficient volume of blood collected
- Skin incision
- Blot the drop of blood
- Used as antiseptic
- Records the time
- Used in Ivy’s Method
A. Lancet
B. Sphygmomanometer
C. Filter Paper
D. Cotton Balls
E. 70% Alcohol
F. Stopwatch
- A
- A
- C
- E
- F
- B
Duke’s Method
- Select the punctured area and disinfect the site with ____
- Without applying pressure on the puncture site, make a firm quick stab to produce a standard ____ deep wound.
- When the blood shows from the punctured site, start timing it using a ____. Do no touch the wound.
- Wait for ____ to lapse and blot the blood coming out of the puncture site with a ____, without allowing the paper to come into contact with the ____.
- Blot the drop every ____. Endpoint is reached when ____.
- Record the time when no more blood appears.
- Select the punctured area and disinfect the site with 70% alcohol.
- Without applying pressure on the puncture site, make a firm quick stab to produce a standard 3mm deep wound.
- When the blood shows from the punctured site, start timing it using a stopwatch. Do no touch the wound.
- Wait for 30 seconds to lapse and blot the blood coming out of the puncture site with a filter paper, without allowing the paper to come into contact with the skin.
- Blot the drop every 30 seconds. Endpoint is reached when no more blood is absorbed by the filter paper.
- Record the time when no more blood appears.
Duke’s Method
Normal bleeding time?
2 to 4 minutes
Some labs say 1 to 3 minutes, it is dependent on the policies.
Duke’s Method
- Squeezing the finger
- Less than 2 to 3 mm depth puncture
- More than 2 to 3 mm depth puncture
- Filter paper touching skin while blotting
A. Falsely prolonged
B. Falsely shortened
- B
- B
- A
- B
Duke’s Method
Prolonged bleeding time is seen in what four (4) phenomena?
- When the blood platelets are greatly reduced
- In injury to capillary wall
- In prothrombin deficiency
- Slightly prolonged severe anemia
Duke’s Method
What are the three (3) diseases/disorders wherein we observe prolonged bleeding time?
- Thrombocytopenia purpura
- Acute Leukemia
- Aplastic Anemia
Duke’s Method
- Bone marrow failure
- Associated with pancytopenia (all types of cell lineage are refuced)
Aplastic Anemia
Duke’s Method
What are three (3) injuries to the capillary wall?
- Scurvy
- Toxins
- Allergy
Which two (2) phenomena can we observe prothrombin deficiency?
- Destructive disease of the liver of the liver with hemorrhagic tendencies
- Hemolytic disease of the newborn
T or F: Bleeding Time test is obsolete internationally.
T
What are the three (3) reasons why bleeding time test lack clinical benefit?
- In the absence of a history of a bleeding disorder, the bleeding time is not a useful predictor of the risk of hemorrhage associated with surgical procedures
- A normal bleeding time does not exclude the possibility of excessive hemorrhage associated with invasive procedure
- The bleeding time cannot be used to reliably identify patients who have recently ingested aspirin or NSAIDs or those who have a platelet defect attributable to those drugs.
- Modification of Duke’s Method (wherein there is increased capillary pressure)
- Provides a very accurate technique if the incisions are identical
Ivy’s Method
Standard pressure of Ivy’s Method
40 mmHg
Ivy’s Method (Part 1)
1.Apply blood pressure cuff on one arm of the patient and inflate to ____, which is to be maintain throughout the test.
2.Let arm to rest on a flat comfortable surface that is well lighted.
3.Choose an area of the ventral part of the arm, preferably near the ____, that does not have visible blood vessels.
4.Disinfect area with ____ and allow spontaneous drying.
5.Make a standard ____ wound with a lancet without hitting any visible blood vessels in the vicinity of the chosen site.
1.Apply blood pressure cuff on one arm of the patient and inflate to 40mm Hg pressure, which is to be maintain throughout the test.
2.Let arm to rest on a flat comfortable surface that is well lighted.
3.Choose an area of the ventral part of the arm, preferably near the antecubital area, that does not have visible blood vessels.
4.Disinfect area with 70% alcohol and allow spontaneous drying.
5.Make a standard 3mm wound with a lancet without hitting any visible blood vessels in the vicinity of the chosen site.
Ivy’s Method (Part 2)
- Start timing when ____
- After ____, blot blood with filter paper.
- Repeat blotting ____ time interval.
- Record time at the point where no more blood adheres on the filter paper (end point).
- Remove pressure cuff and place dry cotton on the puncture site for few minutes.
- Each blot in the filter paper represents ____.
- Report bleeding time as to minutes and seconds the test was completed.
- Start timing when blood appears on the puncture site.
- After 30 seconds, blot blood with filter paper.
- Repeat blotting every 30 seconds time interval.
- Record time at the point where no more blood adheres on the filter paper (end point).
- Remove pressure cuff and place dry cotton on the puncture site for few minutes.
- Each blot in the filter paper represents 30 seconds.
- Report bleeding time as to minutes and seconds the test was completed
- Test to determine the ability of platelets to adhere to glass surfaces
Platelet Adhesiveness/Retention Test
Platelet Adhesiveness/Retention Test
____ is passed through a glass bead column.
Whole blood
Platelet Adhesiveness/Retention Test
Platelet count obtained in glass beads is ____ than obtained by venipuncture.
Lower
Platelet Adhesiveness/Retention Test
Normal value?
26-60%
Platelet Adhesiveness/Retention Test
- Glanzmann’s thrombasthenia
- von Willebrand disease
- Chediak-Higashi Syndrome
- Uremia
- Aspirin Ingestions
Increased or decreased levels of platelet adhesiveness?
Decreased
Platelet Adhesiveness/Retention Test
- Venous thrombosis
- Pulmonary embolism
- Carcinoma
- Pregnancy
- Splenectomy
- Patients taking oral contraceptives
Increased or decreased levels of platelet adhesiveness?
Increased
- Involves serial platelet counts on blood exuding from a forearm incision
- Platelet counts decrease because of platelet adhesion to wound
- Results are compared with a venous blood platelet count
Platelet adhesiveness in vivo
Platelet adhesiveness in vivo
Normal value?
15 to 45%
What is the clinical significance of CRT?
To assess platelet function
CRT is affected by which four (4) factors?
- Clotting Factor Deficiency
- Severe decrease on Platelet count
- Heparin and other anticoagulant treatment
- Asprin and NSAIDs administration
What are the three (3) methods of clot retraction?
- McFarlane method
- Hirschboeck method
- Stefanini method
Please study the procedures of these na lang, I don’t think they’ll ask too much.
Thank you so much mwa. Bow.
- Stimulated by activators such as kaolin and epinephrine.
Platelet Factor 3 Assay
Anticoagulant of choice for PF3?
3.2% Sodium Citrate
What are the four (4) different reagents for PF3?
- 0.025 M CaCl2
- Kaolin
- Epinephrine (109 uM)
- Commercially available normal control plasma or pooled PPP
Please study the procedures for PF3.
Di ko na kaya itype yon hehe labyu sorry mwa.
- A metabollic process wherein binding of any of the agonists to their respective membrane receptors initiates signaling pathways that ultimately convert GpIIb-IIIa
Platelet Aggregation
Upon platelet-to-platelet interaction, platelets change shape from what to what?
Biconvex to sphere (morphological change)
Platelet Aggregation
What are the reagents and equipment for the test for platelet aggregation?
- Platelet Aggregation Reagents
- Cuvettes
- Plastic pipettes
- Plastic test tubes
- Magnetic stir rods
Platelet Aggregation
What are the six (6) platelet aggregation reagents?
- ADP/ATP
- Epinephrine
- Collagen
- Arachidonic acid and ristocetin
- Thrombin/Thromboxane A2
Platelet Aggregation
Uses a special type of photometer to detect the percent transmittance that is being recorded during testing
Aggregometry
Platelet Aggregation
Stirs the plasma with the reagents
Magnetic stir rods
Platelet Aggregation
What are the two (2) special patient requirements?
1.Patient and normal control should be fasting (8 to 10 hours to avoid lipemic samples)
2.Patients should not be taking aspirin or NSAIDs
Platelet Aggregation
All specimens must be drawn using a ____ syringe.
Plastic
Platelet Aggregation
____ is the specimen of choice.
Platelet-rich plasma
You need to observe the aggregation.
Platelet Aggregation
Specimen should be stored at ____.
Room temperature
Match the basic requirements to the reason.
- Hemolyzed samples releases ADP which can prematurely activates platelets
- The calcium content with sodium citrate is still sufficient for aggregation to occur.
- To maintain an optimal activity of the platelet.
- Cooling inhibits the platelet aggregating response. Just before performing the test the plasma is incubated at 37 deg C at the heat block of aggregometer.
- Lipemic plasma may obscure changes in optical density during platelet aggregation.
- In able for aggregation to occur.
A. No hemolyzed sample
B. Plasma from fasting patient is preferred for testing
C. Sodium citrate is the anticoagulant used in aggregation studies.
D. Fibrinogen must be present in the plasma.
E. Aggregated studies should be performed at 37 deg C at a pH of 6.5 to 8.5.
F. Test samples should be maintained at room temp during processing.
- A
- C
- E
- F
- B
- D
Match the basic requirements to the reason.
- The drugs inhibit the platelet release reaction that induces platelet aggregation
- To prevent lost of platelet activity.
- To allow the platelet regain their responsiveness after the preparation procedure
- To maintain the potency of the aggregating reagents.
A. PRP should be allowed to stand for 30 minutes prior to aggregation test.
B. All aggregation studies should be done within 3 hours of sample collection.
C. Aggregating agents should be prepared fresh daily and brought to room temperature
D. Patient should be refrained from taking any antiinflammatory drugs at least 1 week prior to testing
- D
- B
- C
- A
Principle of Platelet Aggregation Test
____ is placed in the test wall of the platelet aggregometer before the aggregating reagent is added.
Platelet rich plasma
Principle of Platelet Aggregation Test
____ is monitored.
Optical density
Principle of Platelet Aggregation Test
When substance that promotes platelet activation and aggregation (agonist) is added to PRP, normal platelets are ____ and ____.
Activated and aggregate.
Principle of Platelet Aggregation Test
Is considered gold standard for platelet function testing.
Light Transmission Platelet Aggregometry (LTA)
Study the procedure for platelet aggregometry.
Please ayoko na.
Interpretation of Results for Platelet Aggregation Test
This measures change in optical density (or light transmittance) of stirred PRP that occurs after addition of agonists.
LTA
Interpretation of Results for Platelet Aggregation Test
Presents change in light transmission (y-axis) against time in minutes (x-axis)
Aggregation Tracing
Interpretation of Results for Platelet Aggregation Test
What are seven (7) parameters to be evaluated?
- Lag phase
- Platelet shape change
- Primary aggregation slope
- Secondary aggregation
- Disaggregation
- Maximum amplitude
- Percent aggregation
Platelet Aggregation
von Willebrand disease and Bernard-Soulier disease affects which agonist?
Ristocetin
Notes on Platelet Aggregation
T or F: We should refrigerate the samples for platelet aggregation.
False
Match the following agonists to their pH.
- ADP
- Epinephrine
- Ristocetin
- Collagen
A. Between 7.7 to 8.0
B. 7.3 but not above 7.7
C. 7.0 to 8.0
- A
- A
- B
- C
Used to quantitate antigens other than
immunoglobulins.
Rocket immunoelectrophoresis (Laurell) for detecting vWF Ag
vWF Ag
- The ____ is incorporated into the agar, and the known antigen is placed in the well and electrophoresed.
- The antigen migrates through the gel, it combines with ____, and forms precipitate forming lateral boundaries in shape of ____
- The distance of antigen migration and precipitation is ____ proportional to the antigen concentration.
- The antiserum is incorporated into the agar, and the known antigen is placed in the well and electrophoresed.
- The antigen migrates through the gel, it combines with antibody, and forms precipitate forming lateral boundaries in shape of rocket.
- The distance of antigen migration and precipitation is directly proportional to the antigen concentration,.
Study the procedures for Rocket immunoelectrophoresis (Laurell) for detecting vWF Ag.
Kaya niyo na yan mwa.
Also known as the tourniquet test.
Rumple-Leed Test/Capillary Fragility Test
Study the procedures for the Ruple-Leede Test.
Last na yan mwa.
Match the following.
- 51+ petechia
- 11-20 petechia
- 21-50 petechia
- 0 to 10 petechia
A. +1
B. +2
C. +3
D. +4
- D
- B
- C
- A
