1. Fetal Haemolytic Disease

2. Maternal antibodies develop against fetal red blood cells IgG antibodies cross the placenta Haemolysis, anaemia, high-output cardiac failure & death

3. Usually a problem with subsequent pregnancies but may occur in the index pregnancy

4. Causes ABO – does not usually cause significant haemolytic disease. Anti-Kell – causes fetal bone marrow aplasia. Rhesus – D antigenanti-D c antigenanti-c E antigenanti-E

5. Incidence Approx 17% of the population is Rh-ve 10% of women at risk of developing anti-D. Incidence 1/1000 pregnancies

6. Predisposing Factors Miscarriage and ectopic pregnancy Invasive procedures ECV Abdominal trauma Antepartum haemorrhage Labour and birth

7. Initial exposure Small IgM response Subsequent exposure Large IgG response

8. IgG crosses placenta Forms antigen-antibody complex on red cell Red cells phagocytosed Anaemia and haemolysis

9. Anaemia Fetal hypoxia Hepatic and cardiac dysfunction Oedema, ascites, pericardial & pleural effusions - HYDROPS

10. Haemolysis Increased bilirubin Jaundice postnatally Kernicterus

11. Prevention Anti-D after any sensitizing episode after 12 weeks Consider routine prophylaxis

12. Management Check antibodies at booking and 3 rd trimester If antibodies present – check antibody levels every 4 weeks to 28 weeks and then 2-weekly to term <4IU/ml – severe disease rare 4-15IU/ml – moderate risk >15IU/ml – 50% risk of severe anaemia

13. Check paternal genotype D antigen autosomal dominant Father DD – fetus Rh positive Father d/D – 50% chance that fetus will be Rh+ve

14. Measurement of blood velocity in middle cerebral artery. Hyperkinetic circulation correlates with fetal anaemia and need for further treatment.

15. Anti-D for sensitising events after 12 weeks. If anti-D antibodies present do not give more anti-D. Serial measurements of Anti-D levels. Observe for signs of fetal anemia – if anemic transfuse or deliver.