What is a TORCH Screen Test?
During pregnancy, infections can be spread from a woman to her developing fetus. Early identification and treatment of these infections in a newborn child is crucial. Prenatal care encompasses a variety of tests, including a TORCH screen test, also known as simply a TORCH test. The TORCH test is also done on newborns.
The TORCH screen is a test that screens for :
- herpes simplex
When it also includes testing for syphilis, it is referred to as a TORCHS test.
While it is typically done on newborns, this test is also ordered if a woman shows symptoms for any of these diseases during pregnancy. These particular diseases can cross the placenta and cause congenital defects. Newborns infected with one of these diseases may be born with cataracts, deafness, mental retardation, heart defects, seizures, jaundice, or low platelet levels.
The test itself screens for antibodies to the diseases, and can provide information as to whether an individual has been recently infected, has had a past infection, or has never been exposed to the infection.
Newer tests for these infections have been developed that are more sensitive and specific than the TORCH test. As a result, the TORCH test is becoming less common. Antibodies can take weeks to develop, and since the test relies on finding antibodies, diagnosis can be delayed.
Diseases Detected by TORCH
Toxoplasmosis is a parasite that typically enters the body through the mouth. Consumption of undercooked meat, raw eggs, and exposure to cat litter or cat feces are possible sources of this parasite.
Rubella, also known as German measles, is a virus that causes a rash. While the side effects of the virus are minor in children, if a fetus is exposed to the virus, it can cause serious birth defects.
Cytomegalovirus, or CMV, is part of the herpes virus group. In adults, it causes flu-like symptoms, but in a developing fetus, it can cause hearing loss, epilepsy, and mental retardation.
Herpes simplex is usually transmitted from the mother to the fetus in the birth canal during delivery. It is also possible for the fetus to become infected in the uterus. Severe symptoms of the nervous system due to this infection typically appear during the baby’s second week of life.
HIV is human immunodeficiency virus. It is the virus that causes AIDS. There is no cure for HIV.
How Is the Test Performed?
TORCH is a blood test. The blood is usually taken from your finger. After cleaning the area, a needle or lancet will be used to draw blood, which is collected in a small tube, on a test strip, or on a slide. You may feel a sharp prick or some stinging during the test. There is typically very little bleeding, but if you are bleeding, a bandage will be applied to your finger.
What Do the Results Mean?
The results are termed either “positive” or “negative.” A positive result means that IgG and IgM antibodies were found for one or more of the infections for which you are being screened. A negative result is “normal,” and means the IgM antibody is undetectable, explains the American Association for Clinical Chemistry.
IgM antibodies show that there is a current or recent infection. If a newborn tests positive for these antibodies, a current infection is the most likely cause. If both IgG and IgM antibodies are found in a newborn, it is a result of maternal antibodies that have been transferred to the baby through the placenta. It does not mean that there is an infection.
During pregnancy, if a woman tests positive for IgM antibody, more testing is done to confirm an infection. There are multiple reasons IgM may be found, and more testing can help determine what kind of treatment is necessary. The presence of IgG antibody in a pregnant woman can mean a past infection. Typically, a second blood test is ordered for two weeks later so the antibody levels can be compared. If levels go up, the infection was recent.
Once an infection is found, the appropriate treatment can be given.