IN THE NAME OF GOD

1. IN THE NAME OF GOD

2. RH ALLOIMMUNIZATION DR.E.ZAREAN

3. Rhesus Blood Group System • First demonstrated by testing human blood with rabit anti sera against red cells of Rhesus monkey & classifying Rh negative & Rh positive. • However the underlying biochemical genetics is not well understood and the genotyping & phenotyping remains little confused. • The genotype is determined by the inheritance of 3 pairs of closely linked allelic genes situated in tandem on chromosome 1 & named as D/d, C/c, E/e (Fisher- Race theory)

4. Pathogenesis Of RhIso-immunisation Rh Negative Women Man Rh positive (Homo/Hetero)   Rh Neg Fetus No problem   Fetus     Rh positive Fetus  Rh+ve R.B.C.s enter Maternal circulation Mother previously sensitized Secondary immune response     Non sensitized Mother Primary immune response ? Iso-antibody (IgG)     ?    Fetus Fetus  unaffected, 1st Baby usually escapes. Mother gets sensitised?   Haemolysis 

5. Pathogenesis Of RhIso-immunisation • Chances of T.P.H/F.M.H. are only 5% in 1st trimester but 47% in 3rd trimester, many conditions can increase the risk. • Chances of primary sensitization during 1st pregnancy is only 1-2%, but 10 to 15% of patients may become sensitized after delivery. • ABO incompatibility and Rh non-responder status may protect. • Amount of antibodies that enter the fetal circulation will determine the degree of haemolysis

6. Pathology Of Iso-immunisation AFTER BIRTH  HAEMOLYSIS  IN UTERO    Jaundice Kernicterus Hepatic Failure ANAEMIA BILLIRUBIN    HEPATIC ERYTHROPOESIS & DYSFUNCTION MAT. LIV NO EFFECT   DEATH IUD       PORTAL & UMBILICAL VEIN HYPERTNSION, HEART FAILURE ERYTHROBLASTOSIS FETALIS         BIRTH OF AN AFFECTED INFANT - Wide spectrum of presentations. Rapid deterioration of the infant after birth. May contiune for few days to few months. Chance of delayed anaemia at 6-8 weeks probably due to persistance of anti Rh antibodies.

7. Factors associated with isoimmunization • Amniocentesis; CVS • Threatened abortion, previa, abruption • Trauma to abdomen • External cephalic version • Multiple pregnancies • Cesarean delivery • Fetal death • Percutaneous umbilical blood sampling • Manual removal of placenta • Hydatidiform mole • EP

8. Prevention of Rh Incompatibility Premarital counseling? Ambitious? Blood grouping must for every woman, before 1st pregnancy. Rh+ve Blood transfusion- 300mcg Immunoglobulin (minimum). Proper management of unsensitised Rh negative pregnancies.

9. Management of Unsensitised Pregnancy • Blood typing at 1st visit, If negative :husband’s typing. If husband is also negative then no treatment • If husband is positive, if possible, Homo/Hetero? • Do Indirect Coomb’s test of mother – • Negative-good. • Repeat ICT at 28 weeks – Negative :300mcg Rh immunoglobulin • PositiveSensitised.

10. Management of Unsensitised Pregnancy ( postpartum ) • If Rh positive(neonate)- Test mother’s blood for ICT & Infant’s for DCT • Negative or weakly reactive- 300mcg immunoglobulin. • Positive – Sensitised–Hb & Bilirubin Estimation of the infant -Treat the infant.

11. Immunoglobulin (RhoGAM) prophylaxis (RhIgG) Schedules • First trimester - 50 μg RhIgG • Amniocentesis - 300 μg RhIgG • Antepartum bleeding • If first trimester - 50 μg RhIgG • If third trimester - 300 μg RhIgG • Postpartum <72 hr - 300 μg RhIgG; 0.1%-%1 require > 300 μg RhIgG

12. Management of Sensitized Pregnancy • Causes of sensitization- • Misinterpretation of maternal Rh type • Rh +ve blood transfusion • Unprotected preg. & labour • Inadequate dose / improper use of IgG on previous occasions • Immunization to cross-reacting antigen

13. Management of Sensitized Pregnancy Careful planning during antepartum, intrapartum & neonatal period Father’s blood type & Rh antigen status Knowledge of maternal antibody titer to the specific antigen Intrauterine foetal monitoring with repeated ultrasound examination, cordocetesis / amniocentesis

14. Management of Sensitized Pregnancy • Fetus Rh Negative: - Observation • Fetus Rh Positive: - • Intrauterine transfusion of ‘Rh Neg’ blood as indicated • Timely delivery any time after 32 weeks • Management of the infant up to 8 weeks • In cases of severely sensitized women, consider medical termination of pregnancy and sterilization .

15. Clinical signs (in fetus) • Anemia • Erythroblastosis fetalis • Ascites • Heart failure • Pericardial effusion

16. Management of Rh negative mother • Maternal antibody titer negative - do serial antibodies • If titer low - little risk of anemia • If > 1:16 - perform amniocentesis and/or Doppler assessment • ∆OD450 plot on Liley curve • Zone I - Rh negative or fetus mildly affected • Zone II - moderately affected • Zone III - high risk for IUFD

19. Fetal management -Rh negative, Ab positive mother Serial sonograms • Early signs • Thickened placenta • Liver span • Increased umbilical vein diameter • Increased blood velocities in UV, aorta and middle cerebral artery • Severe disease - scan every week if hydropic changes. If hydropic changes, consider fetal transfusion.

20. Transfusion therapy Intraperitoneal : • First done in 1963 • Instill blood through needle or epidural catheter • Volume to transfuse = (G.A.-20) x 10ml • Generally, repeat in ~ 10 days, then every 4 wk. • Risk of death about 4% per procedure • Not effective in hydropic fetus • Some advocate combined approach (IPT and IVT)

21. Transfusion therapy Intravascular : • Goal is to have post-transfusion Hct 40-45% • Can infuse about 10 ml/min • Estimate requirement based on EFW and pre-transfusion Hct • Repeat in 1 wk., then about every 3 wk. • Hct falls about 1%/day • Goal: keep Hct > 25% • Smaller volumes, therefore more procedures compared to IPT • Fetal loss about 1.5% per procedure