Rhesus Isoimmunization

1. A (surface antigen A)2. B (surface antigen B)3. AB (antigens A and B)4. O (neither A nor B)

4 Basic Blood Types

ABO System & Pregnancy

hemolytic diseases of the newborn may be due to ABO incompatibility

O + O = O, O + A = O or A, O + B = O or B, O + AB = O or A B

Fetus inherits one gene from each parent.

Rhesus Blood Group System

First demonstrated in Rhesus monkey

Blood group are classified as Rh negative or Rh positive

Rhesus Blood Group System

The genotype is determined by the inheritance of 3 pairs of closely linked allelic genes situated on chromosome 9 named as D/d, C/c, E/e ……….. (Fisher- Race theory)

Rhesus Blood Group System

The gene ( d ) is an amorph & has no antigenic expression. So there are only five effective antigens

Weiner postulates a series of allelic genes at a single locus Rh (D), Rh (C), Rh (E), Rh (c) & Rh (e)

The updated system of Rosenfield refers these antigens as – Rh1, Rh2, Rh3, Rh4, Rh5

Rhesus Blood Group System

The fetus inherits one gene from each group as a haplotype such as sets of Cde, cde etc from each parent

12 sets of combinations & 78 genotypes are possible.

Most frequent genotypes are –

Cde / cde (33%), Cde / cDe (18%), cde / cde (15%), Cde / cDE (12%) cDE / cde (11%), cdE / cde (1%), Cde / cde (1%)

Rhesus Blood Group System

Incidence of Rh negative varies in different races:

Mongoloids > 1, Chinese & Japanese 1-2%, Indians 5%, Africans 5-8%, Caucasians 15-17% & Basques 30-35%.

Rhesus Isoimmunization

Rhesus Iso immunization is an immunologic disease that occurs in pregnancy resulting in a serious complication affecting the fetus / or the neonate ranging from

… mild neonatal jaundice

… to intra uterine loss or neonatal death

Rhesus IsoimmunizationThis immunologic disease occur when a Rh – negative patient carrying a Rh – positive fetus ….. had a feto – maternal blood transfusion

….. the mother immunological system is stimulated to produce antibodies to the Rh antigen on the fetal blood cell

….. This antibodies cross the placenta and destroy fetal red blood cells leads to fetal anemia

…. Usually the 1st fetus will not be affected if this is the 1st time that the mother has been exposed to the rhesus positive antigen

During pregnancy while the fetus still in the uterus The bilirubin in the fetal blood will be removed by the placenta to the maternal circulation and part of it go to the liquor

The fetus will be anemic….. If the degree of anemia is severe fetus may die in utero because of heart failure

After delivery The neonate will affected by …… The degree of the anemia …… The amount of bilirubin

Rh Negative Women

FetusRh Neg Fetus No problem

Rh positive Fetus

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

previously sensitized 2nd immune response

IgM…IgG antibodies

Non sensitized Mother Primary immune response

1st Baby usually escapes. Mother gets sensitized?

Fetus

Haemolysis

Pathogenesis Of Rh Iso - immunisation

Man Rh positive (Hetero)

Antigen-Antibody reaction on the RBCs surface Hemolysis

IN UTERO

Anemia

Hepatic erythropoesis & dysfunction

Portal & Umbilical Vein Hypertension … Heart Failure

Erythroblastosis fetalis

IUD

Polyhydramnios

After birth

Anemia … Jaundice … Kernicterus

Neonatal death

Hemolysis

Antigen-Antibody reaction on the RBCs surface

Management of rhesus negative pregnant women

Management of non sensitized Pregnancy

Management of sensitized Pregnancy

Non sensitized Rh Neg. mothers married to a Rh Pos. husband

… If husband is Rh Positive then… Check Husband being Homozygous or Heterozygous .... Check for maternal antibodies by indirect Comb's test ( ICT ) … if antibodies detected treat as sensitized … If no antibodies Repeat ( ICT ) at 28 and 32 weeks provided that no bleeding. … If there is bleeding then …..

Management of non sensitized Pregnancy

Management of non sensitized Pregnancy

Bleeding after 20 weeks of gestation …….. Check for fetal red blood cells in maternal circulation by Kleihauer test…….. Check for maternal antibodies ( ICT ) … if negative…….. Give ( 500 IU / 100 mcg ) anti D to the mother within 72 hours from the bleeding…….. The dose should be doubled or tripled if fetal RBCs are more than 80 cells in maternal circulation

Prophylactic Management of non sensitized Pregnancy

During antenatal period Prophylactic (500 IU / 100 mcg ) Anti Dare recommended to be given to all

negative non sensitized mothers married to Rh positive husband at 28weeks and 34 weeks to protect and overcome any asymptomatic or un noticed antenatal feto maternal blood transfusion

Management of non sensitized Pregnancy

Precaution should be taken to prevent the possibility of increased chance of feto - maternal blood transfusion At birth

During labor… No fundal pushing in 1st or 2nd stage of labor… No uterine massage or uterine grasp and squeeze in 3rd stage … Let the placenta to be delivered spontaneous … A void avulsions of the cord … Protect the vaginal and perineal wounds and laceration from being exposed to the fetal blood spilled from cord

Management of non sensitized Pregnancy

During cesarean section

… Use abdominal packs in the sides of the uterus before opening the lower segment to prevent spilled blood from the placenta to inter the peritoneal cavity.

… Let the placenta to be delivered spontaneous using control cord traction without squeezing the uterus … A void avulsions of the cord

Management of non sensitized Pregnancy

At birth ……. Maternal blood sample for …….. antibodies by indirect Comb's test ( ICT ) …….. fetal red blood cells in maternal circulation

……. Cord blood sample ( Neonatal blood sample ) for …….. antibodies by Direct Comb's test ( DCT ) …….. Infant blood group …….. Infant bilirubin level …….. Infant Hb & Hct level

Management of Sensitized Pregnancy

Sensitized Rh Negative mothers

If antibodies level start to increase … Arrange for amniocenteses … Spectrophotometer to study the optical density of the amniotic fluid ( i.e. bilirubin level which reflect RBCs haemolysis )… U/S Scan evaluation of the fetal well beings

USS can detect…..…. Fetal Skin and scalp edema, ……... Fetal Ascites, ……... Fetal Pericardial or pleural effusion…….. Polyhydramnios…….. Fetal hepatosplenomegaly…….. Fetal Cardiomegaly…….. Placental hypertrophy and enlargements …….. Abnormal fetal posture (Buddha stance)

Ultrasound scan (USS)

AmniocentesisIs an Indirect method to measure the degree of haemolysis of the fetal red blood cells by measuring the Concentration of bilirubin in the amniotic fluid.

Amniocentesis

Amniotic fluid sample taken and sent for Spectrophotometer

Where optic density of the fluid changes according to the amount of the bilirubin concentration

Amniocentesis

Cordocentesis

Fetoscopy

The first pregnancy with a Rhesus positive baby is significant for a rhesus negative woman because she can be sensitized to the Rh positive antigen. about 13% of Rhesus negative mothers are sensitized by their first pregnancy with a rhesus positive baby.

about 5% of the second Rhesus positive infants of Rhesus negative woman, would result in still births or extremely sick babies and many babies who managed to survive would be severely ill

If no prevention measures were taken during antenatal period

By using anti-RhD immunoglobulin (Rho(D) Immune Globulin) the incidence is massively reduced .

Rh disease sensitization is about 10 times less likely to occur if the fetus is ABO incompatible with the mother than if the mother and fetus are ABO compatible.

Thank you and God Bless you all!