Physicochemical properties (descriptors) in QSAR.pdf
Haemolytic disease of the new born
1. NSLS 200: Blood bank
Haemolytic Disease of the New
Born (HDN)
by Charity Tandiwe Matimbe
BMLS: Africa University
Zimbabwe
2. INTRODUCTION
• Haemolytic disease of the new-born (HDN/erythroblastosis
fetalis) is a blood problem in new-born babies whereby
baby's red blood cells break down at a fast rate.
• It is a subtype of alloimmune anaemia
• According to Medicosis Perfectionalis 25% of all pregnancies
have HDN and only 10% causes anaemia and require
treatment.
3. Types of HDN
• There are two types of HDN that are:
1. ABO incompatibility that leads to HDN which is more
common but less severe
2. Rh incompatibility that leads to HDN which is less common
but severe
4. ABO INCOMPATIBILITY HDN
• ABO HDN can occur during the first pregnancy and subsequent
pregnancies because the mother does not need to be sensitized
• In ABO incompatibility scenario that leads HDN:
The mother is blood group O, this means
-the mother neither has antigen A nor antigen B on the surface of her
Red blood cells
-the mother will produce Anti-A and Anti-B antibodies if her baby is either
blood group A or blood group B
5. • If the baby is blood group A:
- Anti-A containing IgG with an FC component crosses through the
placenta to the baby’s blood
- In baby’s blood there is antigen A on the surface of the Red blood cells
- The antigen A will specifically bind to the Anti-A from the mother, to form
a weak antigen-antibody complex and result in weak agglutination
- The anti-A will destroy the RBC because the FC component attracts a
macrophage that has a FC receptor
- The macrophage produces lytic enzymes that lyse the Red blood cells
and cause extravascular haemolysis result in mild or no anaemia
7. • The anaemia is mild or not at all because the antibody when it gets into
baby’s blood will either bind to the other tissues and the remaining few will
bind to antigen A
• This will then result in fewer weaker antigen-antibody interactions, lesser
agglutination, lesser haemolysis thus occurrence or mild or no anaemia
- The lysis of the Red blood cells produces the heme and the globin
- Heme further breaks down into iron and globin is broken down into
protoporphyrin
- Protoporphyrin breaks down into unconjugated bilirubin (UCB)
- If the placenta and liver cannot fully metabolize UCB the baby will be born
jaundiced
• ABO HDN cannot be prevented
8. RH INCOMPATIBILITY HDN
• In Rh HDN the first pregnancy act as sensitizer if the mother
is
1. Transfused Rh positive blood
2. Does not have any ruptured ectopic pregnancy
3. Placenta abruption
4. Or abortion
• For Rh HDN, a mother who is Rh- and a Rh+ husband
might have Rh- or Rh+ child
9. • If the baby is Rh+ means it has D antigens on the surface of the Red blood
cells
• The mother during first pregnancy starts to produce anti-D due to the
exposure of the D antigens in the baby’s Red blood cells
• Once the mother is sensitized
1. First baby has 0% chance of getting HDN
2. Second baby has 3% chance of getting HDN
3. Third baby has 10% chance of getting HDN
- From the given trend given it can be summarized that as subsequent
pregnancies occur, the chances of the baby getting HDN also increases if
there is a Rh- mother and Rh+ father
• Therefore once the mother is sensitized, for the second and subsequent
pregnancies the response will be faster and stronger
10. • After the sensitization, in the case of a second pregnancy if a Rh- mother has a
Rh+ baby pathogenesis occurs as follows:
1. The anti-D produced by the mother diffuses through the placenta and gets into
the baby’s blood
2. Anti-D strongly attaches to the baby’s antigen on the surface of the Red blood
cells
3. The antigen-antibody complex agglutinates
4. Macrophages bind to the FC component of the antibody
- In this scenario the Macrophage produces lytic enzymes that will lyse the whole
Red blood cell and no spherocytes are produced
- A severe anaemia if pathogenesis occurs is experienced and in some cases a
baby may be a hydrops fetalis
- The baby might as well have pathological neonatal jaundice if UCB produced
from haemolysis is not fully metabolized
11. • Rh HDN can be prevented if :
1. The mother is not sensitized RhO (D) immunoglobulin (RHOGAM) is
administered at 28-30 weeks of pregnancy and at delivery
- RHOGAM is administered so that when the D antigens are introduced in the
mother’s system she will not produce more of the D antigens therefore prevent
sensitization during pregnancy and the other subsequent pregnancies
- D antigens in RHOGAM also do not cross the placenta
2. If the mother is already sensitized NO RHOGAM IS ADMINSTERED
- Exchange transfusion is done to maintain a normal level of the anti-D between
the mother and baby
- repeated titers and amniocentesis are done for the management of the anti-D
- Repeated spectrometric analysis of amniotic fluid
12. DIAGNOSIS OF HDN
• Full blood count
Haemoglobin levels : Low
Haematocrit : Low
UCB: high
Haptoglobin : High
Albumin : Low
• A direct Coombs test is done for ABO HDN and a weak positive is detected because of the
weak antigen-antibody interactions
• Direct and indirect Coombs test for Rh HDN are strongly positive because of the strong antigen-
antibody interactions
• Peripheral blood film on the umbilical cord blood
-spherocytes are observed in ABO HDN
- Nucleated red blood cells in Rh HDN
