• Isoimmunization due to feto-maternal transfusion means formation of antibodies in the mother against her baby.
• ABO system there is natural antibody which is mainly IgM that cannot cross placenta. Where in the Rh. system there is acquired antibodies.

1. Scenario:

• Rh –ve = mother.
• Rh +ve = fetus.

Reaction will occurs leads to hemolysis & the end result is:

1. Hydrobs fetalis (frog-like appearance): caused by sever hemolysis of fetal RBCs.
2. Sever hemolytic anemia (icterus gravis neonatorum): there is high level of unconjugated billirubin that can deposit in the basal ganglia causing (kernicterus). This type need blood exchange transfusion inutero or after delivery to reduce risk of heart failure. Some called (icterus gravis interference).
3. Mild hemolytic anemia: treated by phototherapy.

1.1. Isoimmunization occur:

1. After delivery.
2. At abortion or ectopic pregnancy.
3. During the course of pregnancy especially after 34wks.
4. Due to interference:
   1. E.C.V.
   2. Amniocentesis.

2. IN PRIMIGRAVIDA

• In any booking for both PG or MG blood grouping is mandatory because:
  • Pt. may need transfusion.
  • To know Rh. factor.
• If the Rh. +ve (no problem).
• If the Rh. -ve in primigravida there is no or slightly affect on the fetus, but you should take cord blood sample at time of delivery for:
  • Fetal Hb.
  • Blood group.
  • Billirubin.
  • Direct coomb's test for antibodies.
• If we find that the fetal Rh. +ve to Rh. -ve of his mother we should give  anti-D globin 300mcg to the mother to destroy fetal RBCs.
• If we find that fetal Rh. -ve as his mother there is nothing to do it.

3. IN MULTIGRAVIDA:

• In multigravida & during the course of pregnancy we do indirect coomb's test each 4wks from 24^thwks.
• If the test is +ve that is mean there is antibodies against fetal blood therefore we should do amniocentesis.
• If there is risk of death terminate pregnancy or do intra uterine transfusion. If there is no risk take cord blood sample at time of delivery for:
  • Fetal Hb.
  • Blood group
  • Billirubin
  • Direct coomb's test for antibodies

4. Indications of blood exchange:

1. Preterm.
2. Billirubin level.

If there is mild jaundice treat the baby by photometry or phenobarbitone as enzyme inducer.