Hematologic System

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← HEMATOLOGY TEST

← By:

← Bacolod Ornopia

← Gequillana Steinbach

← 1. Blood typing/ RH typing

← Blood is often grouped according to the ABO blood typing system. This method breaks blood types down into four categories:

← Type A

← Type B

← Type AB

← Type O

← Blood typing is also done to tell whether or not you have a substance called Rh factor on the surface of your red blood cells. If you have this substance, you are considered Rh+ (positive). Those without it are considered Rh- (negative).

← This test is done to determine a person's blood type. Health care providers need to know your blood type when you get a blood transfusion or transplant, because not all blood types are compatible with each other. For example:

← If you have type A blood, you can only receive types A and O blood.

← If you have type B blood, you can only receive types B and O blood.

← If you have type AB blood, you can receive types A, B, AB, and O blood.

← If you have type O blood, you can only receive type O blood.

← The procedure (Forward typing)

← 2. Blood smear

← When a peripheral blood sample is smeared on a slide and stained, it is known as a peripheral blood film. It allows for examination of the physical characteristics of the red cells, white cells and platelets under the microscope.

← Additionally, it helps detect parasites or abnormal cells in the blood. Thus the peripheral blood film is an important indicator of hematological and other disease.

← Blood smear

← 3. Coagulation test

A. Bleeding Time Test

← Bleeding time is a very popular blood test that is primarily used to gauge the speed with which the blood is able to clot.

← The clotting of blood incorporates the functionality of a number of factors such as coagulation factors, platelets, as well as small vessel vasospasm.

← Methods of bleeding time test

← I. Duke’s Method (2-5 mins.)

← II. Ivy Method (3-11 mins.)

← III. Modified Template Method

← b. Activated partial thromboplaSTIN TIME TEST

← Test for the intrinsic and common pathways of coagulation.

← Blood samples are collected in tubes with oxalate or citrate to arrest coagulation by binding calcium. The specimen is then delivered to the laboratory. In order to activate the intrinsic pathway, phospholipid, an activator (such as silica, celite, kaolin, ellagic acid), and calcium (to reverse the anticoagulant effect of the oxalate) are mixed into the plasma sample. The time is measured until a thrombus (clot) forms. This testing is performed by a medical technologist.

← C. PROTHROMBIN TIME TEST

← Test for the extrinsic pathway of coagulation.

← The plasma is analyzed by a biomedical scientist on an automated instrument at 37°C, which takes a sample of the plasma. An excess of calcium is added (thereby reversing the effects of citrate), which enables the blood to clot again. For an accurate measurement the proportion of blood to citrate needs to be fixed; many laboratories will not perform the assay if the tube is underfilled and contains a relatively high concentration of citrate. If the tube is underfilled or overfilled with blood, the standardized dilution of 1 part anticoagulant to 9 parts whole blood is no longer valid. For the prothrombin time test the appropriate sample is sodium citrate tube, which is a liquid anticoagulant.

← D. THROMBIN TIME TEST

← The thrombin time (TT), also known as the thrombin clotting time (TCT) is a blood test that measures the time it takes for a clot to form in the plasma of a blood sample containing anticoagulant, after an excess of thrombin has been added. It is used to diagnose blood coagulation disorders and to assess the effectiveness of fibrinolytic therapy. This test is repeated with pooled plasma from normal patients. The...
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