Aim ; Estimation of Bleeding Time (B.T)

& Clotting Time (C.T) with Discussion.

Dr. Laxmikanta Say

What is the clinical significance of doing BT & CT ?

1. History of frequent, persistent or spontaneous bleeding

2.Before every minor and major surgery -(e.g. tooth extraction)

3.Before taking biopsy -( bone marrow, liver, kidney etc.)

4.Before and during anticoagulant therapy5.Family history of bleeding disorder

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BLEEDING TIME (B.T)Definition ; - time interval between the skin puncture and

spontaneous , unassisted stoppage of bleeding.

Method ; “Duke’s method”, Other methods ; “ivy” Bleeding timeApparatus Required ; - sterile finger prick, clean filter paper, stop

watch.Procedure;Precautions;Normal bleeding time ; 1 – 5 min. 3

CLOTTING TIME ( C.T )

Definition ; - time interval between entry of blood into glass

capillary tube, or a syringe, and formation of fibrin threads.

Method ; Wright’s capillary glass tube Other Methods ; Duke’s Drop method, Lee and

White test-tube method Apparatus Required ; - 10-12 cm long, glass capillary tube with uniform

diameter, stop watch Procedure ; Normal Clotting Time ; 3 – 6 min.

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PROTHROMBIN TIME (P.T)

Normal P.T ; 15 – 20 sec.

Clinical Significance ; bleeding tendency occurs below 20% (Normal plasma prothrombin = 30- 40 mg/dl)

Low prothrombin suggest Vit. K def. and liver and biliary diseases.

Prolonged suggests deficiency of factor II, V, VII, and X.

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DISCUSSION

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WHAT IS HOMEOSTASIS ?

“milieu interieur”

Maintenance of nearly constant conditions in the internal environment.

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WHAT IS HEMOSTASIS ?

Haema = bloodStasis = to haltThe process of stoppage of bleeding.

It is the process of forming clots in the wall of damaged blood vessels & preventing blood loss while maintaining blood in a fluid state with in the vascular system.

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What are the stages of Hemostasis ?

1. Vasoconstriction ( contraction of injured blood vessels )

2.Platelet plug formation

3.Formation of blood clot

4.Fibinolysis ( dissolution of the clot )9

Factors responsible for Contraction of blood vessels !

1. Mechanical stimulation of smooth muscle fibers

2.Local reflexes by stimulation of pain and sensory fibers.

3.Release of potent vasoconstrictors from platelets

- serotonin, epinephrine, thromboxane A2 , prostaglandins, endothelins.

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Platelet plug formation: platelet adhesion

Platelet plug formation: platelet release action

Platelet plug formation: platelet aggregation

Clotting FactorsFactor I Fibrinogen

Factor II Prothrombin

Factor III Thromboplastin

Factor IV Calcium

Factor V Labile factor, or proaccelerin

Factor VI Non – existent

Factor VII Stable factor or proconvertin

Factor VIII Antihaemophilic factor / globulin A

Factor IX Christmas factor or Antihaemophilic factor B

Factor X Stuart – Prower factor

Factor XI Plasma thromboplastin antecedent or Antihaemophilic factor C

Factor XII Hageman factor or Contact factor

Factor XIII Fibrin stabilizing factor or Laki – Lorand factor

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Mechanism of blood Coagulation

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Why blood does not clot in circulation ?

1.Endothelial surface factor -smoothness -layer of glycocalyx -Negatively charged2.Velocity of circulation3.Natural anticoagulants4.Activation of Fibrinolytic system5.Liver removes activated clotting

factors

Bleeding Disorders

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Name the conditions where bleeding time is prolonged and clotting time is normal ? 1. Low platelet count

2.Functional platelet defect ; i.Drugs : aspirin, large dose of penicilin ii.von Willebrand disease iii.others : uremia, cirrohosis, leukemia 3. Vessel wall defects ; i. Prolonged corticosteroid trt. ii. Allergic purpura iii. Infections : typhus, bacterial endocarditis iv. Deficiency of Vit – C v.Connective tissue diseases 18

Name the conditions where clotting time is prolonged and bleeding time is normal ?

1. Hereditary coagulation disorders i. Hemophilias ii. von Willebrand disease iii. Afibrinogenemia or dysfibrinogenemia 2. Acquired Coagulation disorders i. Vit – K def. ii. Liver disease iii. Intravascular clotting iv. Anticoagulant therapy 3. Newborns

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Vit-K dependent factors

Factor - II, VII, IX, X

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Cofactors

HMW Kininogen ,F-V, F-VIII, Protein-S,

Tissue factor, Platelet lipid

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Inhibitors

Protein-C, Antithrombin-III,Extrinsic Pathway Inhibitor

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Hemophilia – A (Classic Hemophilia)

Factor VIII deficiency

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Hemophilia – B ( Christmas disease)

Factor – IX deficiency

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Hemophilia - C

Factor – XI ( Plasma thrombo plastin anticedent ) deficiency.

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Hemophilia - D

Factor – XII ( Hageman factor) deficiency

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Purpura

Definition - purple coloured petichial hemorrhages and

bruises in the skin. - blood leaks out from capillaries

Causes - thrombocytopenia, functional platelet defects,

allergy, old age

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Types

Pathologic I. Primary – idiopathic , ITP (antibody formation)

II. Secondary – Drugs, chemicals, bone marrow depression, excess destruction, hypersplenism

Forms or Classification 1. Thrombocytopenic Purpura

2. Athrombocytopenic Purpura 3. Thromboasthenic Purpura 4. Haemorrhagic Telangiectasis 28

THANK YOU

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