Download - Bleeding Time & Clotting Time
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
2
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.
4
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.
5
DISCUSSION
6
WHAT IS HOMEOSTASIS ?
“milieu interieur”
Maintenance of nearly constant conditions in the internal environment.
7
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.
8
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.
10
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
14
Mechanism of blood Coagulation
15
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
17
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
19
Vit-K dependent factors
Factor - II, VII, IX, X
20
Cofactors
HMW Kininogen ,F-V, F-VIII, Protein-S,
Tissue factor, Platelet lipid
21
Inhibitors
Protein-C, Antithrombin-III,Extrinsic Pathway Inhibitor
22
Hemophilia – A (Classic Hemophilia)
Factor VIII deficiency
23
Hemophilia – B ( Christmas disease)
Factor – IX deficiency
24
Hemophilia - C
Factor – XI ( Plasma thrombo plastin anticedent ) deficiency.
25
Hemophilia - D
Factor – XII ( Hageman factor) deficiency
26
Purpura
Definition - purple coloured petichial hemorrhages and
bruises in the skin. - blood leaks out from capillaries
Causes - thrombocytopenia, functional platelet defects,
allergy, old age
27
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
29