Blood draw
CMV (IgG and IgM)
CMV-IgM and IgG; recent or past infection.
€ 45,00
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Infections · Blood
CMV IgG
Antibodies that show whether you have ever had an infection with cytomegalovirus (CMV).
At a glance
- Measured in blood
- In 1 test panel
- No special preparation
Explanation
CMV IgG: what is measured?
Cytomegalovirus (CMV) is a herpes virus that is passed on through saliva, urine and other body fluids, especially from young children. After an infection, the virus stays dormant in the body and can become active again later, usually without symptoms. IgG antibodies (immune proteins) appear shortly after the IgM antibodies and remain detectable for life. So a positive IgG shows that you have had CMV at some point, not when.
What can it detect?
- Past CMV infection; the virus is present in the body in a dormant state
- No previous infection: chance of a first infection, relevant when you want to have children or during pregnancy
- Together with IgM and an avidity test: sign of a recent infection
Result
What does the result mean?
Positive result
A positive result means that you have had a CMV infection at some point, usually without noticing it. The antibodies do not fully protect you: the virus can become active again and you can be infected with another type of CMV. During a pregnancy, the baby can therefore still become infected, but that chance is much smaller (0.2 to 2 percent) than with a first infection during pregnancy (about 30 percent). If IgM is also positive, it may be a recent infection and further testing is needed.
Negative result
A negative result usually means that you have not had a CMV infection yet. This is normal: about 60 in 100 women of childbearing age have no antibodies. There is no vaccine. In the population, the chance of a first CMV infection during pregnancy is less than 1 percent; good hand hygiene after contact with saliva and urine of young children reduces that chance. Shortly after an infection, the test can still be negative.
After an abnormal result
A positive IgG without IgM usually needs no follow-up. With a positive IgM or a suspected recent infection during pregnancy, the GP or midwife arranges further blood tests and refers you to the gynecologist. CMV is not notifiable.
Reliability
How reliable is the test?
The IgG test reliably shows whether someone has ever been infected with CMV, but not when; for that, IgM, an avidity test or comparison with a previously taken blood sample is needed. According to the LCI guideline (RIVM) on CMV infection, a positive IgG is no guarantee that the unborn baby is protected, because reactivation and reinfection occur. Because there is no treatment that prevents transmission to the unborn baby, a result before or during a pregnancy without symptoms changes little in the advice.
What can affect the result?
- Shortly after a first infection, IgG may not yet be detectable.
- After a blood transfusion or administration of immunoglobulins, antibodies from donors can temporarily be measured as well.
- Tests and cut-off values differ between laboratories; a weakly positive result is sometimes hard to interpret.
Who it is for
Who is the test useful for?
Useful for
The result says the most with symptoms that may point to a CMV infection, such as prolonged fever, tiredness and swollen glands, in a pregnant woman with a suspected infection, and in people with a reduced immune system or before a transplant. As a general test before or during pregnancy, including for employees in healthcare or childcare, the result has few consequences: hand hygiene is the advice for everyone, regardless of the result. Even after possible contact with CMV during pregnancy, an antibody test says little.
How common is it?
About 40 in 100 women of childbearing age in the Netherlands have antibodies against CMV; in women with a Caribbean or Mediterranean background, this is much more common. About 1 in 200 newborns has a congenital CMV infection, some 1,000 children per year, of whom about 180 have lasting effects, such as hearing loss or a developmental delay.
LCI guideline (RIVM) on CMV infection
Drawbacks and risks
- A positive IgG can wrongly give the idea that an unborn baby is fully protected.
- Without symptoms or pregnancy, the result has few consequences, but it can raise unnecessary questions or follow-up tests.
Get tested
CMV IgG: test panels
CMV IgG is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.
Evidence
Sources
This explanation is based on Dutch guidelines and independent information. It is general information, not a diagnosis. Discuss an abnormal result with your GP.
More about risks and resultsMore explanations
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