Bleeding time,clotting time, PT, and PTT
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Bleeding time,clotting time, PT, and PTT Dr. Ayham Abu Laila. Hemostasis or haemostasis. Is a complex process which causes the bleeding process to stop. It refers to the process of keeping blood within a damaged blood vessel. .

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Bleeding time,clotting time, PT, and PTT Dr. Ayham Abu Laila

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Bleeding time,clotting time, PT, and PTT

Dr. Ayham Abu Laila


Hemostasis or haemostasis

  • Is a complex process which causes the bleeding process to stop.

  • It refers to the process of keeping blood within a damaged blood vessel.


Hemostasis is maintained in the body via three mechanisms:

  • Vascular spasm - Damaged blood vessels constrict.

  • Platelet plug formation - Platelets adhere to damaged endothelium to form platelet plug (primary hemostasis) and then degranulate.

  • Blood coagulation - Clots form upon the conversion of fibrinogen to fibrin, and its addition to the platelet plug (secondary hemostasis).


THE CLOTTING MECHANISM

INTRINSIC

EXTRINSC

Collagen

Tisue Thromboplastin

XII

XI

VII

IX

VIII

X

V

FIBRINOGEN

(I)

PROTHROMBINTHROMBIN

(III)

(II)

FIBRIN


FIBRINOLYTIC PHASE

  • ANTICLOTTING MECHANISMS ARE ACTIVATED TO ALLOW CLOT DISINTEGRATION AND REPAIR OF THE DAMAGED VESSEL.


HEMOSTASIS

  • DEPENDENT UPON:

  • Vessel Wall Integrity

  • Adequate Numbers of Platelets

  • Proper Functioning Platelets

  • Adequate Levels of Clotting Factors

  • Proper Function of Fibrinolytic Pathway


So What Causes Bleeding Disorders?

  • VESSEL DEFECTS

  • PLATELET DISORDERS

  • FACTOR DEFICIENCIES


VESSEL DEFECTS

  • VITAMIN C DEFICIENCY

  • BACTERIAL & VIRAL INFECTIONS

  • ACQUIRED


PLATELET DISORDERS

THROMBOCYTOPENIA (INADEQUATE NUMBER OF PLATELETS)

Causes

  • DRUG INDUCED

  • BONE MARROW FAILURE

  • HYPERSPLENISM

  • OTHER CAUSES


THROMBOCYTOPATHY

)ADEQUATE NUMBER BUT ABNORMAL FUNCTION .(

causes

  • UREMIA

  • INHERITED DISORDERS

  • MYELOPROLIFERATIVE DISORDERS

  • DRUG INDUCED(ASPIRIN, NSAIDS)


Inherited:

HEMOPHILIA A

HEMOPHILIA B

VON WILLEBRAND’S DISEASE

Acquired:

Anticoagulant therapy

Liver diseases

DIC

FACTOR DEFICIENCIES


LABORATORY EVALUATION

  • PLATELET COUNT

  • BLEEDING TIME (BT)

  • Clotting time (CT)

  • PROTHROMBIN TIME (PT)

  • Activated PARTIAL THROMBOPLASTIN TIME (APTT)


PLATELET COUNT (CBC)

NORMAL 100,000 - 400,000CELLS/MM3

< 100,000Thrombocytopenia

50,000 - 100,000Mild Thrombocytopenia

< 50,000Sever Thrombocytopenia


BLEEDING TIME

PROVIDES ASSESSMENT OF PLATELET COUNT AND FUNCTION

NORMAL VALUE

2-8 MINUTES


Clotting time - capillary method

  • Material

  • Sterile disposable pricking needle or lancet.

  • Stop watch

  • Dry glass capillary tube (narrow diameter 1 top 2 mm, minimum 10 cm long.)

  • Cotton Swab of absorbent cotton.

  • Spirit wetted, cotton swab.

  • 70 % v/v ethyl alcohol


Clotting time of whole blood


Clotting Time - Slide Method

  • The surface of the glass tube initiates the clotting process. This test is sensitive to the factors involved in the intrinsic pathway

  • The expected range for clotting time is 4-10 min.


PROTHROMBIN TIME

  • Measures Effectiveness of the Extrinsic Pathway

  • NORMAL VALUE

  • 10-15 SECS


PT

  • The prothrombin time: is therefore the time required for the plasma to clot after an excess of thromboplastin and an optimal concentration of calcium have been added.

  • Measures the function of the Extrinsic Pathway.

  • Sensitive to Factors I, II, V, VII, X.

  • The PT evaluates patients suspected of having an inherited or acquired deficiency in these pathways.


THE CLOTTING MECHANISM

INTRINSIC

EXTRINSC

Collagen

Tisue Thromboplastin

XII

XI

VII

IX

VIII

X

V

FIBRINOGEN

(I)

PROTHROMBINTHROMBIN

(III)

(II)

FIBRIN


When is it ordered?

  • Used to monitor oral anticoagulant therapy (Warfarin / Coumadin).

  • When a patient who is not taking anti-coagulant drugs has signs or symptoms of a bleeding disorder.

  • When a patient is to undergo an invasive medical procedure, such as surgery, to ensure normal clotting ability.


An elevated prothrombin time may indicate the presence of:

  • Vitamin K deficiency

    (Vitamin K is needed to make prothrombin and other clotting factors)

  • DIC

  • liver disease

  • a deficiency in one or more of the following factors:

  • I, II, V, VII, X.

  • Anticoagulant (warfarin)


INR

  • A PT test may also be called an INR test.

  • INR (international normalized ratio) stands for a way of standardizing the results of prothrombin time tests, no matter the testing method.

  • So your doctor can understand results in the same way even when they come from different labs and different test methods.

  • Using the INR system, treatment with (anticoagulant therapy) will be the same. In some labs, only the INR is reported and the PT is not reported


  • An INR of 1.0 means that the patient PT is normal.

  • An INR greater than 1.0 means the clotting time is elevated.

  • INR of greater than 5 or 5.5 = unacceptable high risk of bleeding,whereas if the INR=0.5 then there is a high chance of having a clot.

  • Normal range for a healthy person is 0.9–1.3, and for people on warfarin therapy, 2.0–3.0, although the target INR may be higher in particular situations, such as for those with a mechanical heart valve.


PARTIAL THROMBOPLASTIN TIME

Measures Effectiveness of the Intrinsic

Pathway

NORMAL VALUE

25-40 SECS


PTT

  • Thepartial thromboplastin time (PTT) oractivated partial thromboplastin time(aPTTorAPTT( is a performance indicator measuring the efficacy of both the "intrinsic" and the common coagulation pathways.

  • It is also used to monitor the treatment effects withheparin a majoranticoagulant.

  • Kaolin cephalin clotting time (KccT) is a historic name for the activated partial thromboplastin time


THE CLOTTING MECHANISM

INTRINSIC

EXTRINSC

Collagen

Tisue Thromboplastin

XII

XI

VII

IX

VIII

X

V

FIBRINOGEN

(I)

PROTHROMBINTHROMBIN

(III)

(II)

FIBRIN


  • Normal PTT times require the presence of the following coagulation factors:

    I, II, III, IV, V, VI, VIII, IX, X, XI, & XII


When is it ordered?

  • When a patient presents with unexplained bleeding or bruising,

  • It may be ordered as part of a pre-surgical evaluation for bleeding tendencies,

  • When a patient is on intravenous (IV) or injection heparin therapy, the APTT is ordered at regular intervals to monitor the degree of anticoagulation.


Prolonged APTT may indicate:

  • use ofheparin.

  • antiphospholipid antibody:especiallylupus anticoagulant, which paradoxically increases propensity tothrombosis

  • coagulation factor deficiency ,

    e.g hemophilia

  • DIC

  • Liver disease


THE CLOTTING MECHANISM

INTRINSIC

EXTRINSC

Collagen

Tisue Thromboplastin

XII

XI

VII

IX

VIII

X

V

FIBRINOGEN

(I)

PROTHROMBINTHROMBIN

(III)

(II)

FIBRIN


Inherited:

HEMOPHILIA A

HEMOPHILIA B

VON WILLEBRAND’S DISEASE

Acquired:

Anticoagulant therapy

Liver diseases

DIC

FACTOR DEFICIENCIES


  • HEMOPHILIA A (Classic Hemophilia)

    • 80-85% of all Hemophiliacs

    • Deficiency of Factor VIII

    • Lab Results - Prolonged PTT


  • HEMOPHILIA B (Christmas Disease)

    • 10-15% of all Hemophiliacs

    • Deficiency of Factor IX

    • Lab Test - Prolonged PTT


  • VON WILLEBRAND’S DISEASE

    • Deficiency of VWF & amount of Factor VIII

    • Factor VIII is bound to vWF while inactive in circulation; Factor VIII degrades rapidly when not bound to vWF

    • Lab Results - Prolonged BT, PTT


ANTICOAGULANTS

  • An anticoagulant is a substance that prevents coagulation; that is, it stops blood from clotting

  • This prevents deep vein thrombosis, pulmonar embolism, myocardial infarction and stroke.

  • ANTICOAGULANTS

  • Coumadins (Vitamin K antagonists)

  • Heparin


Coumadins

  • These oral anticoagulants that antagonize the effects of vitamin K.

  • Examples include warfarin. It takes at least 48 to 72 hours for the anticoagulant effect to develop. Where an immediate effect is required, heparin must be given concomitantly.

  • Monitored by PT times

  • These anticoagulants are used to treat patients with deep-vein thrombosis (DVT), pulmonary embolism (PE), atrial fibrillation (AF), and mechanical prosthetic heart valves.


Heparin

  • Heparin is a biological substance.

  • It works by activating antithrombin III, which blocks thrombin from clotting blood.

  • Heparin Therapy is Monitored by PTT times

  • Low molecular weight heparin is a more highly processed product that is useful as it does not require monitoring of the APTT coagulation parameter (it has more predictable plasma levels) and has fewer side effects.


Liver Disease

  • Liver Disease can Result in Reduced Production of Coagulation Factors (I,II,V,VII,IX,X).


DIC

  • Disseminated intravascular coagulation (DICis a pathological activation ofcoagulation) blood clotting) mechanisms that happens in response to a variety of diseases

  • DIC leads to the formation of small blood clots inside the blood vessels throughout the body

  • The small clots also disrupt normal blood flow to organs (such as the kidneys), which may malfunction as a result


  • As the small clots consume coagulation proteins and platelets, normal coagulation is disrupted and abnormal bleeding occurs from the skin the gastrointestinal tract, the respiratory tract and surgical wounds.

  • The PT and APTT are usually very prolonged and the fibrinogen level markedly reduced

  • High levels of fibrin degradation products, including D-dimer, are found owing to the intense fibrinolytic activity stimulated by the presence of fibrin in the circulation.


Definitive diagnosis depends on the result of DIC:

  • Thrombocytopenia) prolonged bleeding time)

  • Prolongation ofprothrombin timeandactivated partial thromboplastin time

  • A lowfibrinogen concentration

  • Increased levels offibrin degradation products


THANK YOU


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