The greed test (or avidity test) is a test that, through the analysis of a blood sample, assesses the concentration of IgG antibodies and therefore allows to evaluate whether the infection by Cytomegalovirus it is recent or has already passed for more than a few months.
When is it done?
You undergo this test when a previous examination detects the presence of IgM negative – parameter indicating that the infection is not in progress – e Positive IgG, which instead signal an infection that has already occurred. the greed test therefore serves to find out if the infection has occurred in the three to four months earlier or even earlier.
During a pregnancy it is very important to trace an alleged period of infection. In fact, if the Cytomegalovirus infection occurs in the first half of pregnancy, the virus it can be passed on to the fetus in development (the case studies speak of a 30-40% chance). Transmission itself is not a sentence, as not all infected fetuses develop symptoms, but in the most unfortunate cases the consequences can be very serious and vary from congenital malformations, cognitive delaysdeafness blindness up to abortion.
Knowing more or less when a pregnant woman suffered the infection therefore helps to have a clearer picture of the situation.
The collection of venous blood is analyzed in the laboratory and the result is expressed according to a numerical value that corresponds to the measurement of thegreed of IgG. Low greed indicates a recent infection, while high greed indicates an infection that occurred later in time (over 4 months).
The reference values are:
- Less than 0.150: low (or weak) greed.
- From 0.150 – 0.250: average greed.
- Greater than 0.250: high (or strong) greed.