What Is a TORCH Screen?
A TORCH screen is a panel of tests for detecting infections in pregnant women. Infections may be passed on to a fetus during pregnancy. Early detection and treatment of an infection can prevent complications in newborns.
TORCH, sometimes referred to as TORCHS, is an acronym of the infections covered in the screening:
- other (HIV, hepatitis viruses, varicella, parvovirus)
- rubella (German measles)
- · herpes simplex
A doctor usually performs some components of the TORCH screen routinely when a woman has her first prenatal visit. They may perform other components if a woman shows symptoms of certain diseases during the pregnancy. These diseases can cross the placenta and cause birth defects in the newborn. These conditions include:
The tests screen for antibodies to infectious diseases. Antibodies are proteins that recognize and destroy harmful substances, such as viruses and bacteria.
Specifically, the tests screen for two different antibodies: immunoglobulin G (IgG) and immunoglobulin M (IgM).
- IgG antibodies are present when someone has had an infection in the past and is no longer acutely ill.
- IgM antibodies are present when someone has an acute infection.
A doctor can use these antibodies along with a woman’s history of symptoms to assess if the fetus has been exposed to an infection.
Toxoplasmosis is a disease caused when a parasite (T. gondii) enters the body through the mouth. The parasite can be found in cat litter and cat feces, as well as in undercooked meat and raw eggs. Infants infected with toxoplasmosis in the womb usually don’t show any symptoms for several years. Symptoms, which occur later in life, can include:
- vision loss
- mental retardation
Rubella, also known as German measles, is a virus that causes a rash. The side effects of this virus are minor in children. However, if rubella infects the fetus, it can cause serious birth defects such as:
- heart defects
- vision problems
- delayed development
Cytomegalovirus (CMV) is in the herpes virus family. It usually doesn’t cause noticeable symptoms in adults. However, CMV can result in hearing loss, epilepsy, and intellectual disability in a developing fetus.
The herpes simplex virus is usually transmitted from the mother to the fetus in the birth canal during delivery. It’s also possible for the baby to become infected while it’s still in the womb. The infection can cause a variety of serious issues in infants, including:
- brain damage
- breathing problems
Symptoms typically appear during the baby’s second week of life.
The other category can include several different infectious diseases, such as:
All of these diseases can be spread from the mother to the fetus during pregnancy or delivery.
The TORCH viral screens are simple, low-risk blood tests. You may experience bruising, redness, and pain at the puncture site. In very rare cases, the puncture wound can become infected. There is no risk to the fetus to have this testing.
The TORCH screens don’t require any special preparation. However, tell your doctor if you believe you’ve been infected with any of the viruses covered in a TORCH screen.
You should also mention any over-the-counter or prescription medications you’re taking. Your doctor will tell you if you need to stop taking certain medications or to avoid eating and drinking before the test.
A TORCH screen involves taking a small sample of blood. The blood is usually taken from a vein located in your arm. You will go to a lab and a phlebotomist will perform the blood draw. They will clean the area and use a needle to draw blood. They’ll collect the blood in a tube, or in a small container.
You may feel a sharp prick or stinging sensation when the blood is drawn. There’s typically very little bleeding afterwards. They will apply a light pressure bandage over the puncture site once the draw is complete.
The TORCH screen results show whether you currently have an infectious disease or recently had one. It can also show if you have immunity to certain diseases, like Rubella, from being previously vaccinated yourself.
The results are termed either “positive” or “negative.” A positive test result means IgG or IgM antibodies were found for one or more of the infections covered in the screening. This can mean that you currently have, have had in the past, or have been previously vaccinated against the disease. Your doctor will explain the test results and review with you what they each mean.
A negative test result is generally considered normal, unless it is for a disease that you should be vaccinated against. This means no antibodies were detected, and there’s no current or past infection.
IgM antibodies are present when there’s 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, additional testing will be done to confirm if the baby has the active infection.
If you test positive for IgM antibodies during pregnancy, more testing will be done to confirm an infection.
The presence of IgG antibodies in a pregnant woman usually indicates a past infection or immunity. If there is a question of an active infection, a second blood test is performed a few weeks later so the antibody levels can be compared. If levels increase, it can mean the infection was recent or is currently happening.
If an infection is found, your doctor will create a treatment plan with you specific for pregnancy.