The cytomegalovirus (CMV) is one of the most frequent infectious agents during pregnancy, affecting between 0.5-3.5% of embryos in various European popula­tions [1,2]. It has been estimated that 1/1000 infants in the USA is seriously retarded as a result of congenital infec­tion with CMV [3]. The symptoms of congenital CMV infection vary considerably from case to case, and may include severe congenital cytomegalic inclusion disease with signs of prematurity, jaundice with hepatospleno­megaly, thrombocytopenic purpura, pneumonitis, and central nervous system damage (microcephaly, hydroceph­aly, periventricular calcification, cerebritis, chorioretinitis, optic atrophy, and mental or motor retardation); any com­bination of previously mentioned signs without severe CNS involvement; milder cases which manifest only spleen and liver swelling or behavioral problems [3-6].

On the other hand, in adults the CMV infection usu­ally does not cause any health problems, except in people with an immunodefiency [2,7]. Nevertheless, CMV is widely distributed in Greek and other European popula­tions, in which about 65% of women are carriers of the virus, and represents a rather common serious threat for pregnancies [1,2,7,8].

CMV is a double stranded DNA (dsDNA) virus belonging to the group of the Herpes virus family, which include the Herpes simplex 1 and 2, Varicella zoster, Her­pes type 6 and Epstein-Barr viruses [8,9]. After infection of a white blood cell, the CMV genome either multiplies using the cell DNA and protein synthesis apparatus or it is incorporated by non homologous recombination within the genome of the host cell [8]. There, it may exist in a dor­mant state until reactivated by various factors, including radiation or another viral infection [8].

Both primary and recurrent maternal infections during pregnancy may result in fetal infection. In primary mater­nal infections, the risk for the embryo fluctuates between 25-50%, while in reactivation of CMV infection during pregnancy it is 0.5-3.5% [2,10-12].

Detection of CMV in carriers is performed through laboratory examination of blood, urine, saliva, cerebro­spinal fluid or other secretions or tissues [12]. This includes viral culture (inoculation of human cell culture and check within 20 days), immune testing with quantita­tive analysis of serum anti-CMV IgG, IgM and IgE anti­bodies (using several methods such as enzyme-linked immunosorbent assay (ELISA), radio-immunoassay, immuno-fluorescent assay, immuno-chemiluminescence assay, or immuno-bio-luminescence assay), and CMV DNA testing by polymerase chain reaction (PCR) [13].

The presence of anti-CMV IgG and absence of anti-CMV IgM antibodies in a pregnant woman signifies her immunity to the virus [12,14]. The presence of both IgG and IgM antibodies at high titer signifies sharp current infection [12,14]. Low titer of anti-CMV IgM indicates either a previous sharp infection or the reappearance of a latent infection [12,14].

Since CMV is widely distributed in European popula­tions, a preventive testing strategy during pregnancy is imperative. This includes the quantitative testing of IgG, IgM antibodies in a pregnant woman’s serum at regular intervals. If IgG antibodies are lacking, there is a risk for primary CMV infection. If detection results are positive for IgG and negative for IgM (as in two-thirds of women tested), another regular testing is performed in order to detect any recurrence of infection. If both IgG and IgM are positive, a prenatal test of the CMV DNA by PCR should be performed in an amniotic fluid sample [13-16].

We present here a case of prenatal testing for CMV, which illustrates the necessity of correctly interpreting the preventive immunological and molecular test results, in order to avoid iatrogenic problems.