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Intrauterine Infections (TORCHS and others)
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Many infections (viruses, bacteria, etc.) can pass through the placenta and infect
the fetus - this occurs when the mother has an infection caused by a specific infective
agent, such as a virus. However, there are only five main pathogens that can cause
fetal damage. These organisms are known by the acronym TORCHS - Toxoplasma, Rubella (German measles), Cytomegalovirus
(CMV), Herpes virus,
Syphilis.
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Rubella (German measles)
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In the past, out of all the infective agents, an intrauterine infection with this
virus caused the most fetal damage. The main signs were a reduced head circumference,
defects in the structure of the eye, etc. In recent years, since the introduction
of mass immunization against rubella in the population, intrauterine rubella infection
is rarely seen. Every woman is tested for rubella antibodies in her blood - if she
has not been immunized, she is given the vaccine. It is preferable to do this before
pregnancy, but vaccination at the beginning of pregnancy with an attenuated virus
that cannot damage the fetus can prevent the mother from being infected with the
actual live virus.
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Cytomegalovirus (CMV)
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See separate information sheet.
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Toxoplasma
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Infection with this pathogen usually results from contact with infected cats or
from eating raw meat.
It is expressed in humans as a febrile disease with or without swollen lymph nodes
(lymphadenopathy).
In the fetus, the disease manifests as a disorder of brain development with typical
calcifications (hardenings),
intrauterine growth retardation, enlarged spleen and liver (hepatosplenomegaly),
and many other abnormalities.
The mother's blood antibody level can be measured to check whether she has immunity
against this pathogen and whether she has been infected during pregnancy.
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In cases of suspected infection during pregnancy, the fetus must also be examined
for the presence of infection. This is done by performing amniocentesis to set up
a culture and also to perform a PCR (polymerase chain reaction) test. The amniocentesis
must be performed in the morning and the amniotic fluid sent there in fresh condition
in the afternoon.
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Herpes
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If the mother has a herpes infection that involves the uterine cervix and appears
as vesicles (small blisters) on the cervix, the infant can be infected as it passes
through the birth canal during the birth process. The infection in the infant manifests
as a severe diffuse disease with vesicles on the skin, for which specific treatment
must be given. Delivery by caesarian section can prevent the infant from becoming
infected.
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Syphilis
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This venereal disease used to be common, and was a common cause of congenital defects
in the fetus. All pregnant women in Israel routinely undergo a blood test to screen
for immunity to this pathogen.
These are the main intrauterine infections; however there are others that can also
affect the fetus.
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What are the intrauterine infections other than TORCHS?
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Chickenpox (varicella)
For many years, it was thought that this virus did not damage the fetus. However,
it has recently been found that there is a 2% increase in fetal defects (in excess
of the regular risk) in fetuses exposed to this infection in utero. The main defect
consists of scarified pigmented spots that cover a limited area on the skin, with
or without a shortening of the limb below this area. Eye defects such as reduced
eye diameter and defects in the structure of the head such as a reduced head circumference
associated with ventriculomegaly
may also occur. Most women are immune to this virus because of childhood illness,
even if they were unaware at the time that they were infected. However, if a pregnant
woman comes into contact with a child with chickenpox and it is not known for certain
that she had the illness in childhood, her antibody level must be checked urgently.
If she is not immune, she is given a booster shot of antibodies that protect her
from infection. If the mother contracts chickenpox during pregnancy, testing for
fetal infection can be considered and should be discussed during genetic counseling. This is done by performing
amniocentesis to set up a culture or by testing for antibodies in the fetal blood.
In all such cases a directed ultrasound scan of the limbs, head and ventricles of
the brain, kidneys, heart and eyeballs is recommended.
Parvovirus
Fetal infection involving this virus is rare, and it usually manifests as transient
fetal edema without causing permanent damage.
Other pathogens may rarely
infect the fetus and cause damage, but the probability is very low. These are not
usually tested for unless an ultrasound scan shows suspicious signs such as ventriculomegaly, etc.
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