Blood Groups & Blood Transfusion

Dr. Shaikh Mujeeb AhmedAssistant ProfessorAlMaarefa College

HMIM BLOCK 224

ObjectivesDifferent types of Blood groups blood group

systemExplain blood typing and how it is used to

avoid adverse reactions following blood transfusions.

Describe how blood reactions may occur between fetal and maternal tissues.

Blood Groups and Transfusions

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• In the year 1900, identification of the ABO blood antigen gene explained the observed blood type incompatibilities by Karl Landsteiner

• Today there are 31 different genes known to contribute to the surface features of RBCs determining compatibility between blood types

Blood Group Systems

• Major systems– ABO– Rhesus system(Rh)

• Minor– MN– P– Familial blood groups

Importance of Blood Groups

• Transfusion of blood• Association with disease

• Duodenal ulcers are more common in group O than in A or B

• Tumors of salivary glands, stomach and pancreas are more common in group A than in group O individuals.

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Antigens and Antibodies

• Terms to become familiar with:• Agglutination – clumping of red blood

cells in response to a reaction between an antibody and an antigen

• Antigens – a chemical that stimulates cells to produce antibodies

• Antibodies – a protein that reacts against a specific antigen

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Type B blood

Type AB blood Type O blood

Red blood cell

Red blood cell Anti-B antibody

Antigen A

Anti-A antibody Anti-B antibodyRed blood cellAntigen A

Antigen B

Red blood cell Anti-A antibody

Antigen B

Type A blood

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Red blood cell

Anti-B antibody

(a)

(c) (d)

(b)

Agglutinated redblood cells

Anti-A antibody

Antigen A

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ABO Blood Group

• Based on the presence or absence of two major antigens on red blood cell membranes• Antigen A • Antigen B

Antigens and antibodies of the ABO blood group

Blood Type Antigen Antibody

A A Anti B

B B Anti A

AB A and B Neither Anti A nor Anti B

O Neither A nor B Both Anti A and Anti B

Genotype of ABO blood groups

Blood Group Possible Genotype(s)

A AA, AO

B BB, BO

AB AB

O OO

Landsteiner’s law.

1. If an agglutinogen (antigen) is present on the RBCs the corresponding agglutinin (anti body) must be absent in the plasma

2. If an agglutinogen (antigen) is absent on the RBCs the corresponding agglutinin (anti body) must be present in the plasma

The first law is applicable to all blood groups. But the second part is not necessary always, its true for ABO blood groups.

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Rh Blood Group

• The Rh blood group was named for the rhesus monkey

• The group includes several Rh antigens or factors (Cc, Dd & Ee)

• Rh positive – presence of antigen D or other Rh antigens on the red blood cell membranes

• Rh negative – lack of these antigens

• The seriousness of the Rh blood group is evident in a fetus that develops the condition erythroblastosis fetalis or hemolytic disease of the newborn

Erythroblstosis Fetalis

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Rh-negativewoman withRh-positivefetus

Cells fromRh-positivefetus enterwoman’sbloodstream

In the nextRh-positivepregnancy,maternalantibodiesattack fetal redblood cells

Womanbecomessensitized—antibodies ( + )form to fightRh-positiveblood cells

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Erythroblastosis Fetalis (Hemolytic disease of the newborn-HDN)

• Clinical Features– Edema (Hydrops)– Jaundice– Anemia– Enlarged Liver & Spleen

Erythroblastosis Fetalis (Hemolytic disease of the newborn-HDN)

• Treatment – Exchange blood transfusion

• Prevention– Rh immune globulin (RhIG) injections to the Rh –

negative mother during pregnancy

Blood groups in local populationBlood Group Percentage of Population

O + 48 %

A + 24 %

B + 17 %

AB + 4 %

Rh Positive are about 93% (90-95%)O- 4 %

A- 2%

B- 1 %

AB- 0.23%

Rh negative are about 7% (5-10%)

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Blood transfusion

•Autologus blood transfusion

•Blood grouping and cross matching

•Donor’s RBCs + Recipient’s plasma (major cross matching)

•Recipients RBCs + Donor’s plasma (minor cross matching)

Proffered And Permissible Blood Types For Transfusion

Blood Type of Recipient

Preferred Blood Type of The Donor

Permissible Blood Type of The Donor (In Extreme Emergency)

A A O

B B O

AB A B A,B, O

O O No alternate type

Complications of Blood Transfusion

• Fatal hemolytic reactions in mismatched reactions. • Rapid hemolysis• Jaundice• Renal tubular damage

• Circulatory overload – if rapid transfusion• Hemosiderosis – repeated blood transfusion• Electrolyte disturbances• Transmission of disease

• Hepatitis – B or C• AIDS