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BLOOD PHYSIOLOGYPractical 1

BLOOD GROUPS

By: khulood HusseinBy: khulood Hussein

Phase II Medicine- Blood Module - March 2009

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Clinical significance of determination of blood groups

• At least 30 blood group system contaning 400 (Ag) have been found on the cell membrane of RBCs.

• These can cause Ag-Ab reaction if mixed with plasma that contain antibodies (Ab) against these Ag.

• 2 groups of blood system can cause transfusion reactions more than others: ABO and Rh systems.

Phase II Medicine- Blood Module - March 2009

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ABO Blood GroupsA and B Antigens- Agglutinogens

Phase II Medicine- Blood Module - March 2009

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ABO Blood GroupsRelative frequency of different blood types:

• O 47%

• A 41%

• B 9%

• AB 3%

Phase II Medicine- Blood Module - March 2009

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Agglutinins

Blood type Agglutinogen on RBC

Agglutinin in plasma

A A Anti-B

B B Anti-A

AB A and B None

O None Anti-A and Anti-B

Phase II Medicine- Blood Module - March 2009

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Phase II Medicine- Blood Module - March 2009

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Rh Blood Type• If type D antigen is present on RBC Rh

+ve• Differences between ABO and Rh Ab?• Anti-Rh antibodies are not naturally

occurring Ab.• Previous exposure to Rh antigen is required.

• Rh +ve blood transfusion.• Rh –ve women pregnant with Rh +ve baby.

• Anti-Rh Ab can cross the placenta.

Phase II Medicine- Blood Module - March 2009

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Blood Grouping

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Blood grouping, showing agglutination of cells of the different blood types with anti-A or anti-B agglutinins in the sera

Red blood cell types

Anti-A serum Anti B serum

O - -

A + -

B - +

AB + +

Phase II Medicine- Blood Module - March 2009

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Phase II Medicine- Blood Module - March 2009

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Phase II Medicine- Blood Module - March 2009

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Phase II Medicine- Blood Module - March 2009

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Phase II Medicine- Blood Module - March 2009

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BLOOD TRANSFUSIONS

Phase II Medicine- Blood Module - March 2009

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Blood Transfusion

• Indications.• Types:

–Heterologus–Autologous

Phase II Medicine- Blood Module - March 2009

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Universal Donor.

• Most hospitals have available group O negative blood for use in extreme emergency situations.

• Group O negative is considered as universal donor.

Phase II Medicine- Blood Module - March 2009

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Transfusion Reactions resulting from mismatched blood types

• Agglutination and delayed hemolysis of donor’s RBC (or immediate intravascular hemolysis)→ Jaundice

Phase II Medicine- Blood Module - March 2009

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Phase II Medicine- Blood Module - March 2009

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Diseases transmitted by blood transfusion

• Viral hepatitis

• HIV / AIDS

• Other transmissible diseases are syphilis, malaria.

What do you do to prevent this?

Phase II Medicine- Blood Module - March 2009

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Pre-transfusion Tests

• For a safe blood transfusion, the following tests are done:– Blood grouping

– Cross-matching

Phase II Medicine- Blood Module - March 2009

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X-matching• Once patient’s blood group is known, donor

blood of the same ABO and Rh type is selected.

• Possible donor RBC’s are mixed with the recipient’s serum. If no agglutination, no Ab in recipient blood will attack donor’s RBCs.

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Haemolytic Disease of the Newborn (HDN)

• Rh incompatibility Erythroblastosis Fetalis (HDN).

• Rh –ve lady marrying Rh+ve man.• If baby is Rh+ve, fetal RBC leaks to maternal

circulation during placental separation (delivery or abortion).

• Mother starts to make anti-Rh Ab.• Next pregnancy with Rh+ve baby anti-Rh Ab

pass to baby and cause agglutination and hemolysis of his RBC.

Phase II Medicine- Blood Module - March 2009

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Phase II Medicine- Blood Module - March 2009

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HDN• Clinical picture:

• Anemia→ Jaundice

• Kernicterus (mental

impairment due to precipitation of bilirubin in brain cells)

Phase II Medicine- Blood Module - March 2009

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Prevention• Anti-Rh gamma globulin (RhoGam)

injection given to Rh –ve mothers after delivery of Rh +ve baby.