Clotting time & Bleeding time
1-Clotting time (CT)
The time required for blood to form a clot, it test clot formation which
depend on coagulation factors (figure 1).
• The normal coagulation time in glass tubes is 3 to 10 minutes.
• The whole blood clotting time is a rough measure of all intrinsic clotting
factors in the absence of tissue factors.
• Used in diagnosis of hemophilia (prolonged time to stop).
• Its chief application is in monitoring anticoagulant therapy.
First method uses Capillary tube
Equipment
• Capillary tubes of uniform size (non-heparinized) •
• Alcohol swabs. • Cotton wool. • Plasticine. • A water bath set at 37 C.
Procedure
1- Clean finger with alcohol swap, prick it with lancet and note the time that
the prick is made.
2- Wipe away the first drop of blood. Then while the blood is still flowing
freely place one end of a capillary tube in the blood. Holding the tube
horizontally let it fill by capillary action, fill more than one tube.
3- Close the end of the capillary tube with plasticine. Place the tube in the
water bath. Two minutes after making the puncture, break a capillary tube
and separate the two halves slowly.
4- Repeat the procedure at 60 second intervals with the remaining tubes.
5- When the blood forms a continuous thread like clot between the broken
ends of the tube, the end point has been reached, note the time.
6- The time from pricking the finger to the appearance of the clot thread is
the clotting time.
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Results
• Usually the clotting time measured by this method is in the range 3 - 12
minutes
• Prolong clotting time seen in deficiencies in the intrinsic coagulation
pathway
• Example hemophilia due to deficiency of Factor VIII 8
Second method
Clotting Time using Test Tube Method
• Place 2 ml blood into non-heparinized test tube incubated in water bath
• Every 30 second invert gentle to check for clot formation
• Time from pricking finger to clot formation is clotting time
• Normally 6 -10 min by this method.
When performing a clotting time test, a normal blood clotting time result
is between 8-12 minutes. If the time is prolonged, it may be a manifestation of a
clotting disorder, if it is reduced, it may be the presence of factors that inhibit
clotting or decrease factors
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2- Bleeding time (BT)
Definition:
The bleeding time is the time required for a small cut in the blood vessels
to stop bleeding. When a blood vessel is injured, blood comes out for some
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time and then it stops because of the formation of platelet plug, therefore this test
makes to measure platelet plug formation and condition of vessels. The duration of
bleeding is the bleeding time. Normal value for bleeding time is 1-3 minutes.
Significance:
The bleeding time is mainly used in the diagnosis and treatment of the
haemorrhagic diseases. The bleeding time is also useful just before
operations such as tonsillectomy.
The bleeding time may be performed by following methods: Duke
Method, Ivy Method and Macfarlane Method.
Requirements:
Cotton, needle, filter or bloating paper, stop watch, spirit.
Procedure:
Duke method for bleeding time:
1) The finger tip of the subject is sterilized with spirit and a bold prick is
made with a sterile needle to have free flow of blood.
2) The stop watch is started and time is recorded.
3) A piece of bloating paper is folded into half and exactly at every 30
seconds interval. The blood coming out from the puncture is wiped.
4) The above step is repeated until blood ceases to flow.
5) The time at which blood ceased to flow is recorded.
6) The bleeding time is determined from the recorded time data.
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Report:
The bleeding time of the subject is found to be minutes.
General interpretations of bleeding time are as follows: 1-9 minutes: Normal. 9-15
minutes: Platelet dysfunction. More than 15 minutes: Critical; test must be
discontinued and pressure should be applied.
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Figure 1 Coagulation factors
