Rh incompatibility

Rh incompatibility, cause, manifestations

1. Clinical teaching Rh - incompatibility Anjana Thomas

2. Rh factor The Rhesus factor gets its name from experiments conducted in 1937 by scientists Karl Landsteiner and Alexander S Weiner. Their experiments involved rabbits which, when injected with the Rhesus monkey’s red blood cells, produced an antigen that is present in the red blood cells of many humans.

3. Genotype

4. Definition Rh incompatibility is a condition which develops when there is a difference in Rh blood type between that of the pregnant mother( Rh negative) and that of the fetus ( R h positive)

5. Rh type and pregnanacy A person’s Rh type is generally most relevant with respect to pregnancies If the pregnaant women and her husband are Rh negative, there is no reason to worry about Rh incompatibility If she is Rh negative and her husband is Rh positive, the baby will inherit the father’s blood type, creating incompatibility between mother and her fetus

6. If some of the fetal blood gets into mother’s blood stream, her body will produce antibodies. These antibodies could pass back through the placenta and harm the developing baby’s red blood cells.

7. Usually placenta acts as barrier to fetal blood entering maternal circulation. However, sometimes during pregnancy or birth, fetomaternal haemorrhage can occur. The women’s immune system reacts by producing anti D antibodies that causes sensitization.

8. Causes A difference in blood type between a pregnant woman and her baby causes Rh incompatibility. The condition occurs if a woman is Rh negative and her baby is Rh positive.

9. Risk factor An earlier pregnancy An ectopic pregnancy, a miscarriage or an induced abortion. A mismatched blood transfusion or blood and marrow stem cell transplant. An injection or puncture with a needle or other object containing Rh positive blood

10. Pathophysiology 1 st pregnancy Father RhD + Mother RhD – Fetus RhD + Fetal – maternal blood transfer during labour First newborn RhD + safe But mother RhD – is now sensitized to Rhd antigen

11. Second pregnancy Repeat encounter with Fetal RhD antigen

12. Diagnostic tests The klehauer - betke test or flow cytometry Indirect coomb test The direct coomb test Blood count Billirubin – direct & indirect

13. Signs & symptoms Mildest form Hemolysis Jaundice Total body swelling Respiratory distress Circulatory collapse Kernicterus It occur several days after delivery – poor feeding, decreased activity

14. Manifestations Hydrops fetalis Icterus gravis neonatrum Congenital anemia of newborn

15. Hydrops fetalis This is a most serious from of Rh haemolytic disease. Excessive destruction of the fetal red cells leads to severe anaemia , tissue anoxaemia and metabolic acidosis.

16. Icterus gravis neonatorum This clinical entity is the effect of lesser form of fetal haemolysis . The baby is born alive without evidence of jaundice but soon develops it within 24 hours.

17. Congenital anaemia Mildest form of diseases where the haemolysis is going on slowly. Although anemia develops slowly with in first few weeks

18. Treatment Rh incompatibility is treated with a medicine called Rh immunoglobulin. Treatment for the baby who has hemolytic anemia will vary based on the severity of the condition If Rh incompatibility is diagnosed during pregnancy, mother will receive Rh immunoglobulin in seventh month of pregnancy and again with in 72 hours of delivery.

19. Mother also may receive Rh immunoglobulin if the risk of blood transfer between mother and the baby is high (for example, a miscarriage, ectopic pregnancy, or bleeding during pregnancy)

20. Prevention Immunization with Rh immunoglobulin Prevent or minimize feto maternal bleed Avoid mismatched transfusion Amniocentesis should be done after sonographic localization of placenta

21. Thank you…..