Rh NEGATIVE PREGNANCY

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Rh NEGATIVE PREGNANCY
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• The individual having the antigen on the human
  red cells is called Rh positive and in whom it is
  not present is called Rh negative.
• Incidence In India 5 to 10
• South India 5
• North India 10
• In general 60 of Rh Positive men are
  heterozygous and 40 are homozygous
• Overall Rh Negative women have the chance of
  having an Rh positive fetus is 60 irrespective
  of fathers genotype.

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• Mechanism of antibody formation in the mother
• Antibody formation occurs by iso immunization,
  which is defined as the production of immune
  antibodies in an individual in response to an
  antigen derived from another individual of the
  same species provided first one lacks the
  antigen.
• This occurs in two stages
• Sensitisation
• Immunisation
• In ABO - blood groups naturally occurring anti-A,
  anti-B antibodies are present in the serum.
• But in Rh group there is no such naturally
  occurring antibodies. So for the first time when
  Rh positive fetal red cells enter mothers blood,
  they remain in the circulation for their
  remaining life span. There after they are removed
  by the reticulo-endothelial tissues and are
  broken down with liberation of antigen which
  triggers the iso immunization.
• Since it takes as long as 6 months for detectable
  antibodies to develop the immunization in 1st
  pregnancy is unlikely.
• If the feto-maternal bleed is less than 0.1 ml
  the anti body production sufficient to produce
  iso immunization is unlikely

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• The main effect of Rh antibodies is on the baby
  in the form of hemolytic disease of the new born.
  If the baby is Rh positive and the mother is Rh
  negative, in the sensitized mother the antibody
  becomes attached to the antigen on the surface of
  fetal erythrocytes.
• The effected fetal cells are rapidly removed from
  the circulation by the RE system. Depending upon
  the degree of agglutination and destruction of
  the fetal red cells various types of fetal
  hemolytic diseases appear.
• They are
• Congenital anemia of new born
• Icterus gravis Neonatorum
• Hydrops fetalis

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• Congenital anemia of new born It is the mildest
  form of the disease where hemolysis is going on
  slowly. The destruction of the red cells
  continues up to six weeks after which the
  antibodies are not available for hemolysis. So
  the neonate may require blood transfusion for its
  survival.
• Icterus gravis Neonatorum The baby is born alive
  without evidence of jaundice but soon develops it
  with in 24 hrs of birth. If Bilirubin level rises
  to the critical level of 20 mg/100ml then
  Bilirubin crosses the blood brain barrier to
  damage the basal nuclei of the brain producing
  clinical manifestations of Kernicterus and may
  require exchange transfusion.
• Hydrops fetalis Excessive destruction of the
  fetal RBC leads to severe anemia, tissue
  anoxaemia and metabolic acidosis. These have got
  adverse effects on the fetal heart, brain and on
  the placenta.
• Hyperplasia of the placental tissue occurs in
  an effort to increase the transfer of oxygen.
• As a result of fetal anoxaemia there is
  damage to the liver leading to hypoproteinemia
  which is responsible for generalized oedema
  ascites and hydrothorax. Fetal death occurs
  sooner or later due to cardiac failure. Baby is
  either still born or macerated and even if it is
  born alive dies soon after.

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• Affection in the mother
• Increased incidence of pre-eclampsia,
  Polyhydramnios
• Big size of the baby
• Hypofibrinogenemia due to prolonged retention of
  dead fetus.
• Maternal syndrome or mirror syndrome with
  generalized oedema proteinurea and pruritis.
• Repeated still births
• Repeated abortions.

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• Past history
• History of previous transfusions
• History of previous normal fetus and in
  Subsequent pregnancies fetus presenting as
  hemolytic diseases of new born.
• History of receiving Anti D after delivery
• Signs
• Generalised oedema
• PIH
• Jaundice may be present
• Pruritis
• On abdominal examination
• Polyhydramnios may be present.
• Size of the uterus may be more than the expected.
• In case of a intra-uterine death of fetus FHS
  absent.