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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