Download MBBS Practicals Physiology Tests of Bleeding Disorders

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d i s o r d e r s
Normal Hemostasis

BV Injury

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Tissue
Factor,

Neural

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blood

Blood Vessel

Coagulation

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Platelet

Constriction

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Activation

Activation

Primary hemostatic plug

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Reduced

Thromibn,

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Blood flow

Plt-Fusion

Fibrin

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Stable Hemostatic Plug

5
1. Bleeding Time

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? It is the time taken from the puncture of the

blood vessel to the stoppage of bleeding.

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? The bleeding time test is a useful tool to test

for platelet plug formation and capillary
integrity.

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? BT is more imp. than CT.

? CT concerns the blood only i.e. how firm

the the clot is formed, whereas BT involves

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the interaction of blood with the injured
tissues.
Duke Method

? With the Duke method, the patient is

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pricked with a special needle or lancet,
preferably on the earlobe or fingertip,
after having been swabbed with alcohol.

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? The prick is about 3-4 mm deep. The

patient then wipes the blood every 30
seconds with a filter paper.

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? The test ends when bleeding stops. The

usual time is about 2-6 minutes.
Ivy method

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Clean the anterior surface of the forearm with spirit.
? The blood pressure cuff is placed on the upper arm

and inflated to 40 mmHg.

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? A lancet or scalpel blade is used to make a shallow

incision that is 1 millimeter deep on the anterior of
the forearm.

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? The time from when the incision is made until all

bleeding has stopped is measured and is called the
bleeding time. Every 30 seconds, filter paper or a
paper towel is used to draw off the blood.

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? Normal BT by this method is 3-6 minutes.


Bleeding Time

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Bleeding Time

? A prolonged bleeding time may be a result from

decreased number of thrombocytes or impaired

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blood vessels.

? Bleeding time is affected by platelet function,

certain vascular disorders and von Willebrand

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Disease, not by other coagulation factors.

? Diseases that cause prolonged bleeding time include

thrombocytopenia, disseminated intravascular

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coagulation (DIC).

? Aspirin and other cyclooxygenase inhibitors can

prolong bleeding time significantly.

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Bleeding Time

? People with von Willebrand disease usually

experience increased bleeding time.

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? Von Willebrand factor is a platelet agglutination

protein, but this is not considered an effective
diagnostic test for this condition.

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? It is also prolonged in hypofibrinogenemia.
? Many experts regard the bleeding time as useless, in

that it does not predict surgical bleeding.

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.
2. Clotting Time

? It is the time taken from the puncture of the blood

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vessel to the formation of a fibrin thread.

? A. Capillary Glass Tube Method : Here the blood is

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collected in capillary tube & total time is noted to
form FIBRIN THREADS on breaking tube every 30
seconds. N : 3-8 minutes

? B. Lee & White method : Here venous blood is

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collected in 8 mm diameter glass tube, rocked in a
water bath at 37?C & time is noted from the time of
vene puncture till the blood stops flowing. N : 6-12
minutes.

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Clotting Time

? Mechanism Involved is INTRINSIC Pathway.
? CT depends on presence of all clotting factors.
? It gets prolonged in :

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- 1. Deficiency of clotting factors ? Hemophilia.
- 2. Vitamin K Deficiency ? Factor II, VII, IX & X.
- 3. Anticoagulant overdose.

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? BT & CT is measured before surgery & liver or

bone marrow biopsy.

? PURPURA : BT increased, CT normal.

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? HEMOPHILIA : BT normal, CT increased.


Clotting Time

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? Take home message - All Bleeding

stops.... Eventually