DR.E.ZAREAN

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)

Rh Negative Women Man Rh positive (Homo/Hetero)

Fetus Rh Neg Fetus No problem

Rh positive Fetus

Rh+ve R.B.C.s enter Maternal circulation

Mother previously sensitized Secondary immune response

? Iso-antibody (IgG)

Non sensitized Mother Primary immune response

Fetus unaffected, 1st Baby usually escapes. Mother gets sensitised?

Fetus

Haemolysis

?

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

HAEMOLYSIS IN UTEROAFTER BIRTH

BILLIRUBIN

ANAEMIA

MAT. LIV NO

EFFECT

HEPATIC

ERYTHROPOESIS & DYSFUNCTION

PORTAL & UMBILICAL VEIN

HYPERTNSION, HEART FAILURE

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.

Jaundice

Kernicterus Hepatic Failure

DEATH

ERYTHROBLASTOSIS FETALIS

IUD

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

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.

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 .

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.

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

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

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

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 .

Anemia Erythroblastosis fetalis

• Ascites • Heart failure • Pericardial effusion

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

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.

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)

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