hemostasis and coagulation

Hemostasis and Coagulation

Bleeding time
It is the time that elapses between the puncture of the skin and the stoppage of blood oozing.

Introduction and principle

A standarized puncture of the ear lobe is made and the time need for bleeding to stop is recorded. Cessation of bleeding indicates the formation of haemostatic (platlet) plugs which are in turn rely on an adequate number of platelets and the ability of the platelets to adhere to the subendothelium and to form aggregates.

Methods

1-Duke test(the easiest to perform)
2-IVY test
3- Template test.

Duke Test

Material and Instruments
1-Sterile disposable lancet.
2- Stopwatch.
3-Circular test paper.
4- Alcohol prep pads.

Procedure

1-The ear lobe is disinfected with alcohol sponge and allowed to dry .
2- A standardized puncture of ear lobe is then
made, using a sterile blood lancet.
3-The stopwatch is started at the moment of the puncture.
4-Using a circular filter paper the blood is blotted every 30 seconds without allowing the filter paper to touch the wound.

5- When the bleeding ceases, the stopwatch is stopped and the bleeding time calculated as

the number of blood spots on filter paper divided by 2
Results:
Normal range: 1-3 minutes, borderline times are 3-6 minutes.
Discussion:
What is the clinical significant of determining bleeding time?

Coagulation (Clotting) time

The coagulation time of whole blood is the time required for a measured amount of blood to clot under certain specialized condition.
The aim:
To determine clotting time.

Method

Lee and White method
Materials and Instruments
1-water bath,37 C .
2-glass test tubes, 13*100 mm.
3-stopwatch.
4-plastic syringe (10ml) and 20 gauge needle.
5- fresh whole blood, 4 ml.


Procedure
1-Lable three test tubes with the subject (patient) name, and number them,1,2 and 3.
2-Withdraw 4ml of blood from the subject.
3-Carfully place 1ml of the blood in the test tube 3,then 1ml in test tube 2, and finally, 1 ml in the test tube 1. Start the stopwatch as soon as the blood is placed in the tube 3.
4-Place the three tubes in a 37C water bath.
5-At exactly 5 minutes, tilt test tube 1 gently to 45 angle. Repeat this step every 30 seconds until the test

tube can completely be inverted without spilling the contents( until the blood is completely clotted).
6-Record the time it took for the blood in test tube 1 to clot.
7-Thirty seconds after the blood in test tube 1 is clotted, proceed with test tube 2 and repeat the preceding steps, tilting the test tube every 30 seconds until a clot is formed. Record the results. Repeat this step for test tube 3 as well.
8-Since agitation and handling speed up the coagulation, the coagulation time of test tube 3 is used to report the result.

Results

Normal range 5-11 minutes.

Discussion

1- How can you differentiate between purpura and haemophilia?
2-Test tubes are incubated in water bath at 37C.Why?

Disease

Bleeding time
Clotting time
pupura
increased
normal
Haemophilia
normal
increased
The difference between purpura and haemophilia are: