There are two values reported in the report of the analysis laboratory for the Cytomegalovirus test: IgG and IgM
Cytomegalovirus (CMV) is a virus that causes an infection in itself banal, with very generic symptoms, so much so that often you don’t even realize you have had it.
Cytomegalovirus in pregnancy
If you get sick for the first time in pregnancy, the likelihood of the baby being infected is very low but, if this happens, the risks for the unborn child could be serious, especially if the infection occurred in the first half of pregnancy. To understand if you have already contracted it in the past or if there is an infection in progress, a blood test is done, which looks for the presence of two types of antibodies, called immunoglobulins: IgG and IgM. (Read also: cytomegalovirus and pregnancy)
What are IgG and IgM
IgM they are the antibodies that are produced in the acute phase of the disease, so they are immediately detectable; they remain active for the entire duration of the infection, after which the values gradually decrease, but their presence will continue to be detected in the blood for about 3-4 months (although there are sometimes cases of persistence of the IgM).
The IgG they begin to produce only 1-2 weeks after the infection has occurred, but they will remain present in the organism for life, as a ‘memory’ of the infection that has occurred, and for this reason they will always be detectable in the blood.
What is written in the report
In the report of the greed test of the CMV both the IgM and IgG values are reported, with a result expressed in numbers. Next to the result, they are indicated the reference values used by the laboratory: if it is below that reference value, the result is negative; if it is above, the result is positive.
“Each analysis laboratory uses its own reference parameters, so it is not possible to absolutely indicate which is the numerical limit below or above which the test is negative or positive. For this reason, to be sure of the correctness of the interpretation, it is essential to show the report to the gynecologist “points out Irene Cetin, head of the Obstetrics and Gynecology Unit at the Luigi Sacco Hospital in Milan and Professor at the University of Milan.
Here are the possible outcomes of the test:
- IgM and IgG both negative (i.e. lower than the reference values indicated by the laboratory): it means that the woman has never contracted the infection. This means that he should pay attention to certain preventive hygiene rules, especially if he has frequent contact with small children, who are more prone to get sick.
- IgM negative and IgG Positive: it means that the woman has already contracted Cytomegalovirus in the past but does not have an ongoing infection. “It is the most reassuring case” explains Professor Cetin. “This is because, even if the woman were to become infected again, it would be a secondary infection, which is much less dangerous than the primary one (ie contracted for the first time in pregnancy)”.
- IgM positive and IgG negative: indicates that the woman has never contracted the infection in the past but the infection is now ongoing. “It is a very rare occurrence, since it would mean that the examination was done at the very beginning of the infection, when the IgG have not yet had time to activate”, highlights the gynecologist. “But it is also the most risky occurrence, since it means that it is a very recent infection. It should be emphasized, however, that if the IgM are positive, it is always necessary to repeat a second confirmation test in a specialized center”
- IgM positive and IgG positive: it means that the infection has been there and could still be in progress, as well as it could mean that it occurred up to 3-4 months earlier, given that, as we have said, IgM takes 3-4 months before becoming negative. “In this case, it is essential to try to know as precisely as possible when you contracted the disease” underlines Irene Cetin “and this is possible with an examination called greed test: it may be in fact that the infection dates back to the period of preconception and therefore you can rest assured. If not, a ‘amniocentesis will let you know if the infection has passed to the child. “
Source for this article: consultancy by Irene Cetin, head of the Obstetrics and Gynecology Operational Unit at the Luigi Sacco Hospital in Milan and Professor at the University of Milan.
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