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Clinical Significance Of Blood Transfusion, Plasmaphoresis, Blood Groups And Relevance Of Blood Bank

Updated on January 20, 2014

Blood Transfusion

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Introduction

Blood transfusion is of huge importance in medicine, especially in emergency or life threatening situations. But, before going into its indications, it is paramount the various Coomb’s tests are discussed. Coomb’s test is in two categories: indirect and direct.

Indirect Coomb’s test

This is used for detecting the presence of incomplete antibodies in the serum, eg, Rh antibodies or antibodies in autoimmune hemolytic anemia. The test serum is incubated with saline washed O group Rh positive cells for 1 hour at 370C, washed and a 2% suspension of the sensitized washed red cells is made. One drop of washed cell is mixed with one drop of Coomb’s serum and examined for agglutination by microscopy. A positive test indicates the presence of antibody in the test serum.

Direct Coomb’s test

It is done to find out whether the cells are already sensitized by an incomplete antibody in vivo. The washed red cells are suspended in saline (2% suspension) and one drop of red cell suspension. Agglutination indicates that the cells are already sensitized by the antibodies in vivo.

Blood Compatibility Before Transfusion

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Indications for transfusion

  1. Replacement of whole blood. Sudden loss of 30% of the blood volume (1 liter) demands urgent replacement.
  2. Specific components are indicated under special circumstances when there is selective deficiency of these components.

Blood Diseases With Their Deficient Components

Disease
Deficient Component
Anemia
Packed erythrocytes
Granulocytopenia
Granulocytes
Thrombocytopenia
Platelets
Fibrinogenopenia
Fibrinogen
Hypogammaglobulinemia
Gammaglobulin
Hypoalbuminemia
Albumin

Erythrocyte Components Of Blood

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Blood Components And Erythrocyte Preparations

Blood components

These are red cells, platelets, granulocytes, whole plasma and cryoprecipitate (factor VIII concentrate). Plasma fractions are coagulation concentrates, immunoglobulins and albumin. In many situations specific component therapy is more effective and safer than whole blood. Judicious use of component therapy also helps in making better use of blood, the availability of which is quite scarse.

Erythrocyte preparations

  1. Packed cells with or without the buffy coat
  2. Partially packed red cells
  3. Washed red cells
  4. Frozen red cells
  5. Leucocyte poor and platelet poor red cells.

Leucocyte concentrates: The leucocytes are removed from healthy donors by a process of centrifugation in a cell separator and the plasma is returned to the donor. Granulocyte transfusions are indicated to protect neutropenic patients from infections.

Platelets: Platelet concentrates may be derived either from single units of whole blood or by using a cell separator.

Plasmaphoresis: In this process, only plasma is removed from the donor. Plasmaphoresis can be used as a therapeutic measure to treat circulatory overload, hyperviscosity syndromes, or for removal of circulating immunoglobulins and immune complexes. This method is also employed to obtain high titer immune globulins from suitable subjects.

Blood groups

The outstanding landmark in the history of blood transfusion is the discovery of human ABO blood group system in 1900 by Landsteiner. He differentiated human blood into four distinct groups on the basis of two antigens A and B.

Antigens and antibodies present in each of the four main groups of the ABO system

Blood group
Antigen in red cell
Antibodies in plasma
O
Nil
Anti A; Anti B
A
A
Anti B
B
B
Anti A
AB
A & B
Nil

Subgroups of A

Depending on the strength of antigen, there are subgroups of A, namely a strong antigen A1 and a weaker antigen A2. Hence there are four red cell phenotypes for A, i.e A1, A2, A1B and A2B.

Secretors are individuals who secrete these blood group substances or antigens in the body secretions (80%) whereas non-secretors are those who do not secrete blood group antigens in body secretions (20%). For purposes of testing, saliva is examined.

The specific ABH substances present in the saliva of secretors

ABO group of red cells
Soluble antigen in saliva
O
H
A
A & H
B
B & H
AB
A, B & H

Rh blood group

Following the discovery of the ABO system in 1990, Landsteiner and coworkers described further blood group systems. The human M, N and P antigens were described, but these systems seemed to have little clinical importance. In 1937, Landsteiner and Wiener discovered the rhesus factor by a new method. There are different antigens in the Rh system. Important ones are D, d, C, c, E and e.

Distribution of ABO blood groups in the Caucasian and African Populations

Blood group
Caucasian
African
O
47%
40%
A
42%
22%
B
8%
33%
AB
3%
5%

Blood Bank

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Rh factor: Among the Caucasians, 85% are Rh positive and 15% are Rh negative. In India, especially, Rh negative population is approximately 7% (range 4-10%).

Blood Bank Procedures

Blood bank procedures include

  1. Collection of blood,
  2. Preservation of blood
  3. Separation of components
  4. Cross-matching and
  5. Monitoring the adverse reactions.

ABO and Rh groupings may be done by slide method, tube method or tile-method using specific known antisera and red cells. Detection of incomplete antibodies in the serum and red cells is done by the indirect Coomb’s test and direct Coomb’s test respectively. These are discussed in the next article of this series.

© 2014 Funom Theophilus Makama

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    • AVailuu profile image

      A. Cristen Vailuu 3 years ago from Augusta, Ga

      Any thoughts on autologous therapies?

    • married2medicine profile image
      Author

      Funom Theophilus Makama 3 years ago from Europe

      Yes, I am working on a series on hubs and that topic is included... Thanks for your lovely comment AVailuu

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