BLOOD GROUPS

Types:

Ø      ABO system

Ø      Rh System

Ø      ABO system

Ø      Based upon A and B antigens (agglutinogens) present on cell membrane of RBCs

Ø      Agglutinins are antibodies against A and B antigens present in plasma

Ø      Land steiner law – If an agglutinogen is present then its respective agglutinin will be absent

Ø      Titer of agglutinins at various ages

►    At birth zero

►    Start  producing at 2-8 months of life

►    Maximum by age 8-10 years

►    Start decreasing thereafter

Ø      Prevalence of various blood types (ABO)

►    O         47%

►    A         41%

►    B          9%

►    AB       3%

Ø      Rh system

►    Based upon ‘D’ antigen (Rh factor)

►    Rh positive means presence of  D antigen

►    Rh negative means absence of  D antigen

►    Anti Rh agglutinins are not present in plasma normally

►    Upon first transfusion of Rh +ve blood to Rh –ve person, anti Rh agglutinins are formed and cause sensitization

ERYTHROBLASTOSIS FETALIS

Ø      A haemolysing disorder of fetus and newborn due to blood group incompatibility with mother

Ø      Rh incompatibility

Ø      ABO incompatibility

Rh incompatibility

Ø      Father Rh positive, mother Rh negative ® baby Rh positive

Ø      Haemolysis leads to blast forms of RBCs in fetal blood hence the name erythroblastosis fetalis

Ø      Sensitization of mother during first delivery

Ø      First baby spared

Ø      Increased incidence of disease with subsequent pregnancies with Rh +ve fetus

Ø      Effect of anti Rh antibody on fetal RBCs

Ø      Agglutination of  fetal RBCs

Ø      Haemolysis of agglutinated RBCs and release of bilirubin

Ø      Bilirubin

Ø      Jaundice

Ø      Kernicterus

Ø      Clinical picture

Ø      Jaundice, anemia

Ø      Enlargement of liver and spleen

Ø      Presence in blood of nucleated blastic forms of RBCs

Ø      Mental impairment

Ø      Prevention

Ø      Inj of anti Rh antibody to mother during postpartum period (within 48 hours)

Ø      Treatment

Ø      Replacement of neonate’s blood with Rh negative blood

TRANSFUSION REACTIONS

Ø      Transfusing same blood type

►    Pyrogenic reactions

►    Allergic reactions

►    Circulatory overload (anemic patients, infants)

►    Tetany (citrate intoxication; massive transfusions)

►    Hyperkalaemia (massive transfusions of stored blood)

►    Iron overload (repeated transfusions)

►    Thrombophlebitis

►    Infections (AIDS, hepatitis B,C)

►    Bleeding tendency (dilutional thrombocytopenia with stored blood)

Ø      Transfusing mismatched blood

►    Haemolytic reactions

Ø      Immediate

Ø      With ABO incompatibility

Ø      Without agglutination

Ø      Role of IgM antibodies (haemolysins)

Ø      Activation of compliment system

Ø      Delayed

Ø      With Rh incompatibility

Ø      Haemolysis followed by agglutination

►    Haemolytic reactions

Ø      Clinical Features

Ø      Rigors, fever, Pain in loin, facial flushing

Ø      Jaundice

Ø      Hypotension

Ø      Circulatory chock

Ø      Haemoglobinaemia, heamoglobinurea

Ø      Acute renal shut down, oligurea

Ø      Death