Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Practicals Latest Physiology Tests of Bleeding Disorders
T e s t s o f
b l e e d i n g
d i s o r d e r s
Normal Hemostasis
BV Injury
Tissue
Factor,
Neural
blood
Blood Vessel
Coagulation
Platelet
Constriction
Activation
Activation
Primary hemostatic plug
Reduced
Thromibn,
Blood flow
Plt-Fusion
Fibrin
Stable Hemostatic Plug
5
1. Bleeding Time
? It is the time taken from the puncture of the
blood vessel to the stoppage of bleeding.
? The bleeding time test is a useful tool to test
for platelet plug formation and capillary
integrity.
? BT is more imp. than CT.
? CT concerns the blood only i.e. how firm
the the clot is formed, whereas BT involves
the interaction of blood with the injured
tissues.
Duke Method
? With the Duke method, the patient is
pricked with a special needle or lancet,
preferably on the earlobe or fingertip,
after having been swabbed with alcohol.
? The prick is about 3-4 mm deep. The
patient then wipes the blood every 30
seconds with a filter paper.
? The test ends when bleeding stops. The
usual time is about 2-6 minutes.
Ivy method
Clean the anterior surface of the forearm with spirit.
? The blood pressure cuff is placed on the upper arm
and inflated to 40 mmHg.
? A lancet or scalpel blade is used to make a shallow
incision that is 1 millimeter deep on the anterior of
the forearm.
? 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.
? Normal BT by this method is 3-6 minutes.
Bleeding Time
Bleeding Time
? A prolonged bleeding time may be a result from
decreased number of thrombocytes or impaired
blood vessels.
? Bleeding time is affected by platelet function,
certain vascular disorders and von Willebrand
Disease, not by other coagulation factors.
? Diseases that cause prolonged bleeding time include
thrombocytopenia, disseminated intravascular
coagulation (DIC).
? Aspirin and other cyclooxygenase inhibitors can
prolong bleeding time significantly.
Bleeding Time
? People with von Willebrand disease usually
experience increased bleeding time.
? Von Willebrand factor is a platelet agglutination
protein, but this is not considered an effective
diagnostic test for this condition.
? It is also prolonged in hypofibrinogenemia.
? Many experts regard the bleeding time as useless, in
that it does not predict surgical bleeding.
.
2. Clotting Time
? It is the time taken from the puncture of the blood
vessel to the formation of a fibrin thread.
? A. Capillary Glass Tube Method : Here the blood is
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
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.
Clotting Time
? Mechanism Involved is INTRINSIC Pathway.
? CT depends on presence of all clotting factors.
? It gets prolonged in :
- 1. Deficiency of clotting factors ? Hemophilia.
- 2. Vitamin K Deficiency ? Factor II, VII, IX & X.
- 3. Anticoagulant overdose.
? BT & CT is measured before surgery & liver or
bone marrow biopsy.
? PURPURA : BT increased, CT normal.
? HEMOPHILIA : BT normal, CT increased.
Clotting Time
? Take home message - All Bleeding
stops.... Eventually
This post was last modified on 30 November 2021