3rd Hemato Lab Dentistry)

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Hematopathology

Third Lab

25th Feb, 201227th Feb, 2012


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Bleeding disorders


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A review of the preview lecture


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Bone marrow Blood


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Homeostasis (Hemostasis)


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Homeostasis (Hemostasis)

hemostasis)himostsis, hmstsis(

The termination of bleeding by mechanical or chemical means or bythe complex coagulation process of the body, which consists of:

(a) Vasoconstriction(b) platelet aggregation(c) thrombin and(d) fibrin synthesis.

It is the arrest of the escape of blood by either natural means (clotformation or vessel spasm) or artificial means (compression or ligation)


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Blood within the circulation must remain fluid, but if a blood vessel isdamaged, localized coagulation must take place to prevent loss of blood.

When there is injury to a blood vessel, a series of events is initiated whichresults in controlled hemostasis.

1 Local vasoconstriction2 Adhesion and aggregation of platelets3 Activation of the clotting cascade to form a fibrin clot4 Activation of coagulation inhibitors (coagulation restricted to the site of injury)5 Late fibrinolysis to restore patency of the vessel

These complex interacting systems can be disturbed by:inherited factors or

acquired factors

.Resulting in bleeding or thrombotic disorders


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Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, 7th ed. 2003 by Saunders


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Common acquired coagulopathies:

Disseminated intravascular coagulation Liver disease Vitamin K deficiency


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History in a suspected bleeding disorder:

Type of bleeding: mucocutaneous, hemarthroses/muscle hematomas Severity of bleeding: blood transfusions, anemia

Previous tests of the hemostatic system Operations Dental extractions Trauma

Childbirth Age of onset Family history Other medical problems Drugs: aspirin, non-steroidal anti-inflammatory drugs (NSAID).


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Is the bleeding mucocutaneous (often seen in platelet defects and vWD).or into joints and muscles (often seen in coagulation factor deficiencies)?The age of onset and a family history are important to address the issue of

whether the condition is likely to be inherited or acquired.

Menorrhagia (beginning from the menarche) is much more likely to bedueto an inherited coagulation defect than is menorrhagia (starting later in

life). If there is a family history, the mode of inheritance is important, forexample, X-linked recessive inheritance suggests hemophilia A or B.

The severity must be assessed; did it result in anemia or a bloodtransfusion?


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Conditions which may be mistaken for a coagulopathy !!!

Henoch-Schonlein vasculitis Vitamin C deficiency Steroid purpura/Cushings disease Amyloid in the skin vessels Ehlers-Danlos/pseudoxanthoma elasticum Cryoglobulinemia


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Investigations in suspected abnormal bleeding Screening tests: Full blood count

Prothrombin time Activated partial thromboplastin time Thrombin time or fibrinogen PFA100 closure or bleeding time

Other first line investigations:

Factor VIII, von Willebrand factor )vWF( activity, vWF antigen Platelet aggregation Platelet nucleotides

Second line investigations: Factor XIII

2-antiplasmin


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What mean by:

(a) PT(b) PTT(c) TT(d) BT


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vWD (AD)vWD is a common disorder caused by (reduction or structural abnormality) ofvWF.

vWF has the dual role of promoting platelet adhesion to exposed collagen andprotecting factor VIII in the circulation.

In vWD, the main defect is the resulting abnormal platelet function and ismanifest by mucocutaneous bleeding.

Menorrhagia is common in affected women. Most cases are mild, withsignificant bleeding only occurring after a haemostatic challenge.


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PT prolonged, APTT normal:Deficiency of factor VII (seen in early vitamin K deficiency/oral anticoagulationor liver disease)

PT normal, APTT prolonged:Deficiency of factors VIII, IX, XI (or the contact factors), Lupusanticoagulant

PT prolonged, APTT prolonged (TT normal):Deficiencies of factors (II, V, X), Vitamin K deficiency/oral anticoagulation,Liver disease

PT prolonged, APTT prolonged (TT prolonged):AfibrinogenemiaHeparinDIC

Interpretation of coagulation screening tests


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Megakaryocytes

In stressed thrombopoiesis:

cytoplasm matures quicker than nucleus so that

low ploidy MK start to produce platelets that

are larger, denser and metabolically more activeEach MK CanProduce 3000

Platelets


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Thrombocytopenia Production

Aplastic anemiaLeukemias

ChemotherapyBM infiltration Survival

ITP

Evans syndromeSLEDIC

TTP/HUSSepsis

Loss fromcirculation

SplenomegalyMassive-

Transfusion


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ACUTEChildhood

CHRONICAdult

Peak Age Years 2 6 20 40

Sex M/F 1:1 1:3

Onset Acute Chronic

Preceding Infection Common Unusual

Platelet Count Often 20,000/uL

Spontaneous Remission > 80% < 20%

Usual Duration 2 4 weeks Months/ Years

I T P


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