Lab Eval of Secondary Hemostais

What is secondary hemostasis?

The formation of a stable fibrin clot through the coagulation cascade.

What is the primary purpose of secondary hemostasis?

To stabilize the initial platelet plug through fibrin formation.

Which coagulation factors belong to the intrinsic pathway?

Factors XII, XI, IX, and VIII.

Which coagulation factors belong to the extrinsic pathway?

Factor VII and tissue factor (TF).

Which coagulation factors belong to the common pathway?

Factors X, V, II, I, and XIII.

What is the main output of secondary hemostasis?

Presence of a stable fibrin clot.

What does clotting time measure?

The time required for blood to form a visible fibrin clot.

What does the coagulation test evaluate?

The composite action of all plasma coagulation factors acting simultaneously.

Which platelet component is involved in clotting time despite platelet functions otherwise being excluded?

Platelet Factor 3 (PF3).

What are the two micro methods of clotting time determination?

Slide or Drop Method and Capillary Tube Method.

What is another name for the Capillary Tube Method?

Dale and Laidlaw's Method.

What is the principle of Dale and Laidlaw's Method?

Blood clots inside a narrow glass capillary tube through contact activation.

What is the normal clotting time using the Capillary Tube Method?

3–6 minutes.

How frequently are capillary tube segments broken in the lecture procedure?

Every 30 seconds after 2 minutes.

What is the purpose of breaking capillary tube segments?

To observe the formation of a fibrin strand.

What are the two macro methods of clotting time determination?

Lee-White Method and Activated Coagulation Time.

Why are macro methods considered superior to micro methods?

There is less contamination of plasma with tissue fluids when blood is drawn from a vein.

What is another name for the Lee-White Method?

Whole Blood Clotting Time.

What is the principle of the Lee-White Method?

Fresh blood forms a firm clot in standardized glass tubes at 37°C.

What does the Lee-White Method primarily evaluate?

The integrity of the intrinsic coagulation system.

What is the normal range of Lee-White clotting time?

5–10 minutes.

What are the advantages of the Lee-White Method?

More accurate, standardized, simple, cost-effective, and can be performed with a control.

What are the disadvantages of the Lee-White Method?

Rough method, possible syringe or tube contamination, and sensitivity to environmental factors.

What happens when Lee-White tubes are vigorously agitated?

Clotting time becomes shorter.

What conditions may prolong whole blood clotting time?

Hemophilia A or B, severe liver disease, DIC, anticoagulants, and fibrinogen abnormalities.

What is Activated Coagulation Time (ACT)?

The time required for fresh blood to clot at 37°C with surface contact activation.

What is the normal ACT according to the lecture procedure?

1–2 minutes.

What is the primary coagulation system evaluated by ACT?

The intrinsic coagulation system.

What are the surface contact activators used in ACT?

Kaolin, celite, glass beads, silica, and ellagic acid.

What factors can affect ACT results?

Heparin concentration, platelet count and function, hypothermia, IV fluid dilution, factor deficiencies, and medications.

What is Plasma Recalcification Time (PRT)?

A test that measures the intrinsic coagulation mechanism.

What is the normal PRT?

90–250 seconds.

Why is PRT more useful than whole blood clotting time for detecting some abnormalities?

It is more sensitive and may reveal abnormalities not detected by venous clotting time.

What is Activated Recalcification Time (ART)?

An activated intrinsic coagulation test using platelet-rich plasma, calcium chloride, and celite.

What is the normal ART?

Less than 50 seconds.

What is the function of platelet-rich plasma in ART?

Provides coagulation factors and the PF3 surface.

What is the function of 0.025 M calcium chloride in ART?

Replaces calcium removed by citrate and initiates clotting.

What is the function of 1% celite in ART?

Acts as a contact activator of the intrinsic pathway.

What can prolonged ART indicate?

Intrinsic factor deficiencies, severe liver disease, hypofibrinogenemia, anticoagulants, or platelet functional defects.

What does Partial Thromboplastin Time (PTT) evaluate?

The intrinsic and common coagulation pathways.

What does Activated Partial Thromboplastin Time (aPTT) evaluate?

The intrinsic and common pathways, particularly factors VIII, IX, XI, and XII.

What is the normal aPTT?

25–35 seconds.

Why is Factor XIII not evaluated by aPTT?

Factor XIII acts after fibrin formation to stabilize the fibrin clot.

What does the aPTT reagent bypass?

The extrinsic pathway, including Factor VII and tissue factor.

What is Differential Activated Partial Thromboplastin Time (DAPTT)?

A test used to differentiate factor deficiencies from circulating anticoagulants.

What is Differential Partial Thromboplastin Time (DPTT)?

A modification of aPTT using correcting Factor VIII and Factor IX reagents.

What does correction with Factor VIII reagent suggest?

Hemophilia A due to Factor VIII deficiency.

What does correction with Factor IX reagent suggest?

Hemophilia B due to Factor IX deficiency.

What does correction in a mixing study generally suggest?

A coagulation factor deficiency.

What does failure to correct in a mixing study generally suggest?

The presence of a circulating anticoagulant or inhibitor.

What pathways does Prothrombin Time (PT) evaluate?

The extrinsic and common pathways.

What is the normal PT range in the lecture summary table?

12.6–14.6 seconds.

Which factors can PT detect deficiencies of?

Factors I, II, V, VII, and X.

What is the clinical use of PT?

Monitoring oral anticoagulant therapy and evaluating extrinsic and common pathway deficiencies.

What is the One-Stage Method of Quick also called?

Stanley Brown Method.

What reagents are used in the Quick PT method?

Tissue thromboplastin and calcium.

What is the principle of the Quick PT method?

Tissue thromboplastin and calcium are added to plasma to initiate clot formation.

Which factors may prolong PT when deficient?

Factors V, VII, and X, or severe deficiencies of Factors I and II.

What is the Two-Stage Prothrombin and Proconvertin Test?

Owren and Aas Method.

Which factors are estimated by the Owren and Aas Method?

Prothrombin (Factor II) and Proconvertin (Factor VII).

What are the advantages of the Owren and Aas Method?

More sensitive than Stanley Brown, accepts mailed specimens, and is not affected by heparin.

What is Owren's Thrombotest Method used for?

Monitoring coumarin anticoagulant therapy.

Which method is considered most sensitive for controlling coumarin anticoagulant therapy?

Owren's Thrombotest Method.

What is the Fibrometer Method?

An electromechanical semi-automated method used extensively in the Quick one-stage PT method.

How does a fibrometer detect clot formation?

By sensing changes in electrical conductivity or mechanical resistance.

What is the Prothrombin Time Micromethod used for?

Pediatric patients, using micropipettes.

What is Stypven Time also called?

Russell's Viper Venom Time.

What is the primary use of Stypven Time?

Distinguishing Factor X deficiency from Factor VII deficiency.

Which factor deficiency is not detected by Stypven Time?

Factor VII deficiency.

What other deficiencies can Stypven Time detect?

Deficiencies of prothrombin, fibrinogen, and Factors V and X.

What is Prothrombin Activity or Index?

A percentage-based expression of PT activity, with 100% as the maximum level.

What is the formula for PT activity?

PT activity (%) = Control PT / Patient PT × 100.

What is the International Normalized Ratio (INR)?

A standardized way of reporting PT results for monitoring oral anticoagulant therapy.

What does the International Sensitivity Index (ISI) measure?

The sensitivity of the thromboplastin reagent relative to the international standard.

What does an ISI greater than 1.0 indicate?

Lower sensitivity.

What does an ISI less than 1.0 indicate?

Higher sensitivity.

What is the Prothrombin Consumption Test (PCT)?

A test best considered as an evaluation of platelet phospholipid activity.

What does a short PCT with normal PT and PTT suggest?

PF3 deficiency due to thrombocytopenia or thrombopathia.

What does the Thromboplastin Generation Test evaluate?

The entire intrinsic pathway and the capacity of blood to generate thromboplastin.

What are the two methods of the Thromboplastin Generation Test?

Biggs and Macfarlane Method and Hick's-Pitney Kaolin Modification Method.

What is the main purpose of Thrombin Time (TT)?

To measure the availability of functional fibrinogen.

What is the principle of Thrombin Time?

Commercial thrombin is added to citrated plasma and the time required for clot formation is measured.

What is the normal Thrombin Time?

10–20 seconds.

What is Thrombin Time particularly sensitive to?

Heparin inhibition.

What does prolonged Thrombin Time suggest?

Fibrinogen deficiency or inhibition, or heparin interference.

What is the Fibrindex Test?

A commercial test in which thrombin produces clotting after addition of plasma containing fibrinogen.

What is the normal Fibrindex plasma clotting time?

5–10 seconds.

What is the expected Fibrindex firm clot time without serum?

30–60 seconds.

What is the FIT-test?

An immunological slide test that detects fibrinogen through latex-mediated agglutination.

What indicates the presence of fibrinogen in the FIT-test?

Agglutination.

What is the Fibrinogen Titer Method?

A test using serial plasma dilutions mixed with thrombin to identify the highest dilution producing a visible fibrin clot.

What does the fibrinogen titer indirectly relate to?

Fibrinogen concentration and the presence of circulating anticoagulants.

How is plasma fibrinogen quantitatively measured?

By converting fibrinogen into fibrin and quantifying it using different analytical methods.

What are the methods of plasma fibrinogen assay?

Ellis and Stransky, Stirland's, Turbidimetric Partfantjev, Ratnoff and Menzie, and Fibrin Clot Method.