Laboratory Evaluation Secondary Hemostasis Flashcards
Tests the composite action of all plasma factors
acting simultaneously
the coagulation test
is a measure of the ability of the blood
to clot and is not influenced by the platelet functions
other than PF3
clotting time
measures only the time
required for the formation of the traces of thrombin
sufficient to produce a visible clot.
coagulation test
a. Micro Methods of coagulation test
slide or drop method
capillary or dale and laidlaw’s method
interval for checking fibrin strand in slide method
every 30 seconds
every how many seconds do we need to break capillary tube in capillary tube method
every 30 seconds and check for fibrin strands
Macro Methods of coagulation test
lee-white method or whole blood clotting time
this method of coagulation test is superior for there is less
contamination of the plasma with tissue fluids when
blood is drawn from a vein.
macro methods
principle of the lee white method
the whole blood clotting time is the time required for freshly collected blood to form a firm clot in standardized glass tubes at 37*C. Thus, the whole blood clotting time is a measure of the integrity of the intrinsic system
normal values of lee white clotting time
5-10 mns
- Advantages of Lee Whit
- More accurate and standard method.
- Test can be run with control.
Disadvantages of lee white
- It is also a rough method.
- There can be contamination of syringe or tube.
- Vigorous agitation of the tubes should be avoided as it shortens the clotting time
the principle of Activated Coagulation Time of Whole Blood
the activated coagulation time of whole blood is the time necessary for fresh blood to form a clot when incubated as 37*C in the presence of surface contact activation. This assay, like to whole blood clotting, measures overall activity of the intrinsic clotting system
normal values of Activated Coagulation Time of Whole Blood
1-2 mns
factors that may affect our coagulation test result includes
the effects of surgery
body temperature
other medicines you are taking
getting IV fluids which can dilute the blood
platelet counts and platelet functions
coagulation factor deficiencies
is a measure of intrinsic coagulation mechanism
plasma recalcification time
more sensitive method than the coagulation time of whole blood
plasma recalcification time
may reveal abnormality which is not detectable by the determination of clotting time of venous blood
plasma recalcification time
ref range of plasma recalcification time
90-250 seconds
Activated Recalcification Time employs the use of ___
0.1 ml of plt rich plasma and an activator
activator examples in Activated Recalcification
Time
0.1 ml of 0.025 M calcium chloride
0.1 ml of 1% cellite
reference range of Activated Recalcification
Time
less than 50 seconds
Simple test for the INTRINSIC and COMMON
pathways of coagulation
partial thromboplastin time
a test for the deficiencies of factors in the
INTRINSIC system. (Factor VIII, IX, XI, XII)
activated partial thromboplastin time
normal values of ptt or aptt
24-39 secs or
25-35 seconds
used to differentiate factor deficiency and disorder of
circulating anticoagulants
differential test of activated partial thromboplastin
Another modification of APTT which is done by mixing
the patient’s plasma with commercially available
correcting reagents, Factor VIII and IX reagents.
differential partial thromboplastin time
in a prolonged PTT, and is corrected with factor VIII, the condition is
hemophilia A
in a prolonged PTT, and is corrected with factor IX , the condition is
hemophilia B
measures the EXTRINSIC and COMMON pathway of
coagulation.
prothrombin time
It is used to monitor oral anticoagulant
therapy
protrombin time
. This can detect prothrombin, fibrinogen, Factors V,
VII and X deficiencies.
prothrombin time
the method under prothrombin times
one stage method of Quick (stanley brown method)
principle behind the prothrombin time - one stage method of quick
tissue thrimboplastin and calcium added to plasma react to fibrinogen to form a clot. The thromboplastin added to the plasma takes the place of the tissue juice formation of extrinsic
thromboplasitn. The prothrombin time is therefore prolonged if
there is a deficiency of Factors V, VII or X or a very severe
deficiency of Factor I and II
- It offers a combined estimation of the levels of
prothrombin and proconvertin
Two-stage Prothrombin and Proconvertin Test
(Owren andAas)
It is more sensitive with Stanley Brown Method
Two-stage Prothrombin and Proconvertin Test
(Owren andAas)
ADVANTAGES of Two-stage Prothrombin and Proconvertin Test
(Owren and Aa)
a. It is more sensitive with Stanley Brown Method.
b.Fresh specimens are not necessary, and the method
can be used for mailed samples of blood.
c. The method is not affected by heparin
for the control of Coumarin anticoagulant
therapy, this is considered as the most sensitive test
Owren’s Thrombotest Method
it is an electromechanical semi-automated instrument
that has been used extensively in one-stage prothrombin
method of Quick
Fibrometer Method
this is microtechnique employed for childern and the
method uses micropipettes; the principle of the test is
similar with one-stage prothrombin time or Stypven Time.
Micromethod (Pro time)
- it is used to distinguish deficiencies of Factor X and
those of Factor VII. It is also used to detect deficiencies in
prothrombin, fibrinogen and factors V and X. It differs from
prothrombin time in that deficiencies in factor VII are not
detected
Related Method- Stypven Time (Rusell’s viper venom
Time)
-
reported in percentage, with 100% as the
maximum leve
Prothrombin Activity orInde
this method of reporting has been proposed to
monitor patients on oral anticoagulant therapy
International Normalized Ratio
it is defined as the prothrombin time ratio had the
test been performed using international standard
thromboplastin reagent.
International Normalized Ratio
best considered as a test of platelet phospholipid
activity. If the prothrombin time and the PTT are
normal, a short PCT indicated a deficiency of PF3
due to thrombocytopenia or thrombopathia
Serum Prothrombin Time or Prothrombin
Consumption Test (PCT)
Thromboplastin Generation Test
- Bigg’s and Macfarlane Method
- Hick’s-Pitney Kaolin Modification Method
-measures the availability of functional
fibrinogen
. Thrombin Time
sensitive test in detecting heparin inhibition
Thrombin Time
Principle of
Commercially prepared thrombin reagent is added
to citrated plasma, and the time required for clot
formation is measured.
ref range of thrombin time
10-20 secs
commercially available test wherein upon addition
of plasma containing fibrinogen, thrombin produces
clotting. N
fibrindex test
ref range of fibrindex test
5-10 seconds
firm clot without serum 30-60 secs
a rapid slide test based on the agglutination of
fibrinogen-coated red blood cells by the latex antihuman fibrinogen reagent. Normally, presence of
fibrinogen is indicated by agglutination
fit test
serial dilutions of plasma are diluted with thrombin.
The titers is the highest dilution in which a fibrin clot
can be seen, and is related to the fibrinogen
concentration and indirectly to the presence of
circulating anticoagulants
fibrinogen titer method
several accurate methods are now available for the
quantitative assay of plasma fibrinogen. Fibrinogen is
usually converted into fibrin which is quantified by
gravimetric, nephelometric, chemical, immunologic
and precipitation methods
assay of plasma fibrinogen
Methods of assay of plasma fibrinogen
a. Ellis and StranskyMethod
b. Stirland’sMethod
c. Turbidimetric Method of Partfantjev et.al
d. Ratnoff and Menzie Method
e. Fibrin Clot Method
