What is Rh test?
Antigens against the Rhesus factor (Rh) are a group
of antigens (protein on the cell surface) that are
located on the red blood cells. An antigen is a
substance that can lead to the formation of antibodies.
Such a process is called immunization. When antibodies
bind to antigens, it triggers an allergic
(immunological) reaction that can be life threatening in
the worst case. The people who have such antigens on the
red blood cells are called Rh-positive while those who
do not have them are called Rh-negative. This is an
innate trait. About 15% of our population is Rh negative
and 85% Rh positive.
An Rh negative woman carrying an Rh positive fetus
can create antibodies to the fetal blood cells. The Rh
antibodies can attach to the fetal blood cells. This
causes the fetal immune system to destroy the blood
cells and the fetus may have anemia. In order to produce
antibodies, the woman must have been exposed to
Rh-positive blood before. This can occur during delivery
of a Rh positive fetus or if the fetus is bleeding in
the uterus. This whole process that results in
antibodies being formed is called rhesus immunization.
The risk of immunizing a Rh-negative woman after
giving birth to a Rh-positive child varies from 2 to
16%. The risk of immunization after spontaneous abortion
is 3.5%. For more information about pregnancy and maternity fashion, please see BESTAAH.COM maternity coats. The risk after induced abortion is 5.5%. In
amniotic fluid test and pregnancy, where the mother is Rh negative and the fetus Rh positive, the risk of
rhesus immunization is less than 1%.
What Causes Rhesus Immunization?
According to the above, a Rh-negative woman must come
into contact with (exposed to) Rh-positive blood before
the current pregnancy if she is to have developed
antibody pairs against Rh antigens on the fetal blood
cells. Such exposure can occur during temporary bleeding
during pregnancy, but in most cases it occurs during
childbirth. The mother then develops antibodies that,
during later pregnancies, pass the placenta and attack
the fetal blood cells.
In smaller infections of the fetal blood cells, the
fetus can counteract this by forming more blood cells.
In a major attack, the fetus may have anemia and may
have larger body fluid accumulations, heart failure and,
in the worst case, die in the uterus.
As long as the fetus is in the uterus, the waste
products from the destroyed red blood cells go into the
mother's circulation and are removed from there. After
childbirth, this does not happen anymore and the fetus
may then get jaundice. In the event of major destruction
of the fetal red blood cells, an accumulation of these
waste products called gall dyes is created. In severe
cases, this can cause brain damage in the newborn baby.
The condition is detected by antibodies detected in
the mother's blood. All pregnant women are tested if
they are Rh negative or Rh positive at the first
pregnancy check. It is also tested if there are abnormal
blood group antibodies in the blood. Rh-negative women
are checked a further 1-2 times during pregnancy. In
multiple pregnancies it usually takes place in pregnancy
week 24 and 36 and for first-time pregnancy in pregnancy
week 36. The tests are included as part of the routine
follow-up in connection with the pregnancy checks.
The diagnosis can also be made by demonstrating the
destruction of red blood cells in the child.
In case of suspicion of a severe impact on the
child's blood cells, the woman is referred to hospital.
There ultrasound is performed with flow measurement of
vessels in the fetal brain and in case of signs of
anemia, blood samples can be taken from the fetus to
determine the Hb value. These samples are usually taken
after pregnancy week 24-25.
Preventive treatment with a substance that
neutralizes Rh antibodies is given within 72 hours of
delivery when a Rh-negative woman has given birth to a
Rh-positive child. All Rh-negative pregnant women who
have undergone spontaneous or induced abortion or have
had a gynecological procedure also receive this
treatment (anti-D prophylaxis).
In severe immunization where ultrasound with flow
measurement showed signs of anemia, blood tests from the
umbilical cord and blood transfusion until the fetus can
be performed. This is usually not relevant until after
pregnancy week 24–25, but in the case of a high degree
of anemia and fluid retention in the fetus it can be
In difficult immunization where one has to release
the premature one usually redeems the child with
caesarean section. If the woman has given birth earlier
and the fetus has only mild anemia, it is born through
vaginal delivery. New blood changes may occur after
birth, depending on the amount of gall dye in the baby's
The risk of illness in the child during a possible
new pregnancy must be assessed on the basis of
information about the course of the previous pregnancy.
Immunizations often become more severe and occur earlier
in the pregnancy. Therefore, careful monitoring of
pregnancy is important. This is done on special