Rh blood group system
Prevention of rh incompatibility
• The Rhesus factor gets its name from experiments
conducted in 1937 by scientists Karl Landsteiner
and Alexander S. Weiner.
• Their experiments involved rabbits which, when
injected with the Rhesus monkey's red blood cells,
produced an antigen that is present in the red
blood cells of many humans.
is determined by the inheritance
of 3 pairs of closely linked allelic genes situated
on chromosome 9 named as
……….. (Fisher- Race theory)
• First demonstrated in rhesus monkey
• Blood groups are classified as Rh positive and Rh
• The Rh factor , Rh+ and Rh- usually refers
specifically to the presence or absence of
•There are two alleles, or genetic variants , of
this antigen: D and d.
•A person who is Rh- has two recessive traits,
dd. Anyone who has at least one D-DD or Dd-is
• A person's Rh type is generally most relevant with
respect to pregnancies
• If the pregnant woman and her husband are Rh
negative, there is no reason to worry about Rh
•If she is Rh negative and her husband is Rh
positive,the baby will inherit the father's
blood type ,creating incompatibility between
mother and her fetus.
•If some of the fetal blood gets into mother's
blood stream, her body will produce
•These antibodies could pass back through
the placenta and harm the developing baby's
red blood cells, causing very mild to very
serious anemia in the fetus.
a condition which
there is a
difference in Rh
between that of
negative) and that
of the fetus (Rh
• Usually placenta acts as barrier to fetal blood
entering maternal circulation.However,sometimes
during pregnancy or birth,fetomaternal
haemorrhage (FMH) can occur. The woman’s
immune system reacts by producing anti-D
antibodies that cause sensitisation
•In subsequent pregnancies antibodies can cross
placenta and destroy fetal erythrocytes. The
haemolytic disease of fetus and new born caused by
Rh isoimmunisation can occur during the first
pregnancy, but usually sensitisation during the first
pregnancy or birth leads to extensive destruction of
fetal RBC during subsequent pregnancies
Sign &symptom of Rh
• Rh incompatibility can cause symptoms ranging from
very mild to fatal.
• Mildest form- Rh incompatibility:
1-Hemolysis (Destruction of the red blood cells) with the
release of free hemoglobin into the infant's circulation.
2- Jaundice (Hemoglobin is converted into,bilirubin
which causes an infant to become yellow.
Severe form- Rh
1- Hydrops fetalis (Massive
fetal red blood cell
2- It causes Severe
failure Death of the infant
shortly after delivery.
2- Total body swelling.
3- Respiratory distress (if the infant has been
4- Circulatory collapse.
5- Kernicterus. (Neurological syndrome in extremely
6- It occurs several days after delivery and is
characterized initially by...
A) Loss of the Moro reflex.
C) Decreased activity
At last it may lead to death of the child
immediately after its birth
DETECTION OF Rh INCOMPATIBILITY:
1-There are no any physical symptoms can be
seen in rh incompatibility.
2-If the woman just found out she is pregnant,she
should undergo blood-type test. This test
determines her blood type and Rh factor
3-Blood test that will determine whether she is
Rh positive or Rh negative
-Phototherapy for neonatal jaundice in mild
-Exchange transfusion if the neonate has
moderate or severe disease (the blood for
transfusion must be less than a week old, Rh
negative, ABO compatible with both the fetus
and the mother, and be cross matched against the
-By using special immune globulins,
called -RhoGAM“ at 28 weeks of
-If the baby is born Rh positive,
another dose is administered within 72
hours after delivery. This will prevent
her body from creating any future
antibodies that could cause harm
during a pregnancy
Wrong transfusion can cause agglutination of blood in
the recipient Hence before transfusion of blood, along
with identification of ABO blood group, it is necessary
to test compatibility of Rh factor.