BLOOD PHYSIOLOGY Practical 1 BLOOD GROUPS Phase II

BLOOD PHYSIOLOGY Practical 1 BLOOD GROUPS Phase II Medicine- Blood Module May 2008 1

Objectives • Describe the clinical significance of determination of blood groups. • Name the blood groups of ABO & Rh system. • Describe the principle of determination of blood groups. • Determine blood groups by using anti-A and anti-B antisera. • Mention the common indications of blood transfusion. • List the common hazards of transfusion. • Name the diseases transmitted by blood transfusion. • Describe the concept of universal donor and universal recipient. • Describe the cause of erythroblastosis fetalis. Phase II Medicine- Blood Module May 2008 2

Clinical significance of determination of blood groups • At least 30 commonly occurring antigens (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 Ag can cause transfusion reactions more than others: ABO and Rh systems. Phase II Medicine- Blood Module May 2008 3

ABO Blood Groups A and B Antigens - Agglutinogens Phase II Medicine- Blood Module May 2008 4

ABO Blood Groups Relative frequency of different blood types: • • O A B AB 47% 41% 9% 3% Phase II Medicine- Blood Module May 2008 5

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 May 2008 6

Phase II Medicine- Blood Module May 2008 7

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 May 2008 8

Blood Grouping Phase II Medicine- Blood Module May 2008 9

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 O Anti-A serum Anti B serum - - A + - B - + AB + + 10

Phase II Medicine- Blood Module May 2008 11

Phase II Medicine- Blood Module May 2008 12

Phase II Medicine- Blood Module May 2008 13

Phase II Medicine- Blood Module May 2008 14

BLOOD TRANSFUSIONS Phase II Medicine- Blood Module May 2008 15

Blood Transfusion • Indications. • Types: – Heterologus – Autologous Phase II Medicine- Blood Module May 2008 16

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 May 2008 17

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 May 2008 18

Phase II Medicine- Blood Module May 2008 19

Common Hazards of Blood Transfusion • Acute transfusion reactions occurring within 72 hours: – Immunological reactions : • Haemolytic transfusion reaction • Allergic reactions eg. urticarial reaction – Non immunological reaction: Circulatory overload • Delayed transfusion reactions occurring after 72 hours: – Iron overload – Renal tubular blockage by haemoglobin – Renal failure Phase II Medicine- Blood Module May 2008 20

Diseases transmitted by blood transfusion • Viral hepatitis • HIV / AIDS • Other transmissible diseases are syphilis, malaria, CMV etc. , What do you do to prevent this? Phase II Medicine- Blood Module May 2008 21

Pre-transfusion Tests • For a safe blood transfusion, the following tests are done: – Blood grouping – Cross-matching Phase II Medicine- Blood Module May 2008 22

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. Phase II Medicine- Blood Module May 2008 23

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 24 hemolysis of his RBC.

Phase II Medicine- Blood Module May 2008 25

HDN • Clinical picture: • Anemia→ Jaundice • Hepatosplenomegaly • Kernicterus (mental impairment due to precipitation of bilirubin in brain cells) Phase II Medicine- Blood Module May 2008 26

Prevention • Anti-D antibodies (Rho. Gam) injection given to Rh –ve mothers after delivery of Rh +ve baby. Phase II Medicine- Blood Module May 2008 27

Phase II Medicine- Blood Module May 2008 28