ABO incompatibility

simple presentation explaining ABO incompatibility

1. ABO INCOMPATIBILITY By P.Padma Priyanka

2. CONTENTS INTRODUCTION BLOOD TYPES MODERATING FACTORS DIFFERENCE B/N ABO AND RH INCOMPATIBILITY HS AND ABO-HDN DIAGNOSIS- HISTORY,LABORATORY MANAGEMENT SUMMARY

3. INTRODUCTION ABO-Hemolytic disease of newborn 25% of pregnancies HDN develops only in 1/10 such offsprings O group mother and A/B group fetus Female>male OA>OB Cause-reaction of maternal anti-A/B to antigen present on RBC of fetus or newborn IgG antibodies cross the placenta

4. BLOOD TYPES ABO system in 1990 A,B,AB,O Central principle is ANTIGENS Isoantibodies against isoantigens I mportant for transfusion

5. Co-dominant inheritance of ABO system

6. ABO on 9q34 - glycosyltransferase A- N-acetyl galactosamine B- galactose H on 19 H antigen- precursor Antigens contained in food,bacteria and vaccines

7. MODERATING FACTORS Mild nature and low incidence of ABO-HDN accounts for low antigenicity of AB factors wide distribution fewer antigen sites on preterm RBC

8. DIFF B/N ABO & RH INCOMPATIBILTIES May occur in first born Increasing frequency of disease in subsequent pregnancies is generally not present The subsequent babies may be more effected or less effected or even spared

9. HS AND ABO-HDN Increased osmotic fragility, autohemolysis , splenomegaly in both But autohemolysis is not corrected by glucose as in HS Family history,long -term course,MCHC differentiate HS from ABO-HDN

10. DIAGNOSIS (suspected) Antenatally – Past history of ABO-HDN in previous sibling Titer of anti-A/anti-B in mother is >1:64 Postnatally – Early onset of jaundice <24hrs A/B group baby of O mother Mild splenomegaly Anemia – usually absent

11. DIAGNOSIS (laboratory) Serum bilirubin Reticulocytosis Spherocytosis  Fragility of RBC Confirmation of antibodies-eluted serum Direct coomb’s test Maternal IgG antibodies in ADCC assay Detection of antigen density on RBC High titres of anti-A/B hemolysins -in maternal serum

12. Start intensive phototherapy if bilirubin exceeds 10mg/dl at 12hrs 12mg/dl at 18hrs 14mg/dl at 24hrs 15mg/dl at any time Exchange transfusion-if it reaches 20mg/dl MANAGEMENT

13. Guidelines for phototherapy

14. Guidelines for exchange transfusion

15. SUMMARY INCIDENCE O group mother and A/B group fetus Co-dominant inheritance HS and ABO-HDN Diagnosis Management –phototherapy and exchange transfusion

16. REFERENCES Manual of neonatal care-CLOHERTY Care of new born-MEHERBAN SINGH HARRISON’S principles of internal medicine

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