Blood Groups and Transfusions

Blood Groups and Transfusions. Prof. N. Sudheera Kalupahana June 2021.

Objective: Explain the basis of blood grouping, cross-matching and incompatibility.

Case History. Mrs. Dissanayake , a 30-year-old lady is admitted for the delivery of her 2 nd child. Her 1 st child was delivered at home. The obstetric registrar has asked you to prepare her for an emergency Caesarian Section. You , the house officer, has to get one pint of blood ready..

Determined by antigens on the surface of red cells (agglutinogens).

Blood group incompatibility may cause:. Transfusion reactions.

The A and B antigens (agglutinogens) are inherited as mendelian allelomorphs, A and B being dominants.

ABO System. Blood group o Antigen(s) present on the red blood cells A antigen B antigen A antigen and antigen None Antibodies present in the Anti- serum Anti-B Anti-A None A and Anti-B Genotype(s) AA or AO BB or BO 00.

ABO System. Antibodie present Antigens present Group A Anti-B A antigen Group B Anti-A B antigen Group AB None A and B antigens Group O Anti-A and Anti-B No antigens.

ABO System.

Grouping of Blood. Anti-B Type A Type B Type AB.

Blood Group Antigens on cell Antibodies in plasma Transfuse with group A A Anti-B A or O B B Anti-A B or O AB A and B none AB, A, B or O O None Anti-A & B O.

Case History contd... Mrs. Dissanayake had the Caesarian section (Fortunately!) blood transfusion was not necessary Her newborn was severely jaundiced Mother’s blood group was B negative.

Composed primarily of the C, D, and E antigens. D is by far the most antigenic component.

Rh negative mother carries a Rh positive fetus. Small amounts of fetal blood leaks into the maternal circulation at the time of delivery.

If hemolysis in the fetus is severe, the infant may die in utero or may develop anemia, severe jaundice, and edema (hydrops fetalis).

Preventing Rhesus Incompatibility. All women should have their blood group known prior to delivery If a Rh negative mother gives birth to a Rh positive baby: Anti-D is given to the mother to prevent sensitisation.

Blood Transfusion. ihii.

Indications for transfusion. Hypovolaemia due to loss of blood Severe anaemia.

Serological Testing. Three tests: ABO/Rh Antibody detection/identification Crossmatch.

Crossmatching. Purpose : Prevent transfusion reactions Double checks for ABO errors Another method of detecting antibodies.

Crossmatch. Donor RBCs (washed). Patient serum. No agglutination ~ compatible.

ABO incompatibility reaction – can be rapidly fatal.

ABO and Rh systems are the two major blood groups.