Definition TORCH is an acronym for a special group of infections. These may be acquired by a woman during pregnancy. "TORCH" stands for the following infections:
Children, men, and non-pregnant women can also catch these infections. However, the TORCH infections are mainly important because they can be transmitted to the foetus while it is in the womb. If a mother is exposed to these infections during the first 5 months of pregnancy, serious foetal complications may occur. These include:
Who is a candidate for the test? Any pregnant woman who has been exposed to the above infections may be a candidate for screening. A pregnant woman who believes she has been exposed should speak with her doctor right away.
How is the test performed? A small amount of blood is withdrawn from a vein in the arm. This blood is sent to the laboratory for testing. A blood test called an antibody titre is used to detect antibodies to any the suspected TORCH organism.
An antibody is a special protein made by the immune system that helps fight infections. The body makes specific antibodies in response to specific infections. These antibodies are made in large amounts when an infection occurs. When the initial sample of blood is taken shortly after exposure, the body may not have had enough time to start making antibodies yet. However, a woman can have antibodies to the infection in her blood because of an old infection or from a vaccine.
A second sample of blood is usually taken 10 to 21 days later to see if blood antibody levels or titres against the infection are rising. This generally means that a new infection, instead of an old one, is present. If an old infection is the cause of antibodies in the blood, the level of antibodies will not rise with the second blood sample, as it does with a new infection. This is important, because old infections usually do not result in harm to the foetus, except in the case of herpes. Only infections that are newly caught during the early part of pregnancy usually put the foetus at risk.
What is involved in preparation for the test? No preparation is needed for this test.
What do the test results mean? A "negative" test means that the woman does not seem to have a new TORCH infection. It is important to realise that there are many other causes of birth defects. In other words, a negative TORCH screen does not guarantee a healthy baby.
A positive test means that high or increasing levels of antibodies were detected. This generally means that the mother has caught a new TORCH infection. A positive test does not mean that the foetus will catch the infection or develop birth defects. However, close monitoring of the pregnancy may be advised.
Pregnancy ultrasound may be used to look for birth defects. This is an x-ray test that uses sound waves to look at the foetus inside the womb. The option of ending the pregnancy, or having an elective abortion, may be discussed. The exact risk of having a child with birth defects depends on the specific TORCH infection. It also depends on when during the pregnancy the mother caught the infection. The doctor will discuss the results in the event of a positive test.
Author: Eva Martin, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 26/05/2005 Contributors Potential conflict of interest information for reviewers available on request
