Prenatal diagnosis of congenital cytomegalovirus infection: false-negative amniocentesis at 20 weeks' gestation

Cytomegalovirus and Epstein-Barr Virus Associations with Neurological Diseases and the Need for Vaccine Development

Herpesviruses have been isolated from a wide range of hosts including humans—for which, nine species have been designated. The human herpesviruses are highly host adapted and possess the capacity for latency, allowing them to survive in the host for life, effectively hidden from the immune system. This ability of human herpesviruses to modulate the host immune response poses particular challenges for vaccine development but at the same time proves attractive for the application of human herpesvirus vaccines to certain spheres of medicine. In this review, congenital cytomegalovirus (CMV) infection and hearing loss will be described followed by a comment on the status of current vaccine development. Secondly, the association of Epstein–Barr virus (EBV) infection with multiple sclerosis (MS) and how EBV vaccination may be of benefit will then be discussed. Prevention of congenital CMV by vaccination is an attractive proposition and several vaccines have been evaluated for potential use. Particularly challenging for the development of CMV vaccines are the needs to prevent primary infection, reinfection, and reactivation at the same time as overcoming the capacity of the virus to generate highly sophisticated immunomodulatory mechanisms. Cost and the practicalities of administering potential vaccines are also significant issues, particularly for low- and middle-income countries, where the burden of disease is greatest. An effective EBV vaccine that could prevent the 200,000 new EBV-associated malignancies which occur globally each year is not currently available. There is increasing interest in developing EBV vaccines to prevent MS and, in view of the association of infectious mononucleosis with MS, reducing childhood infectious mononucleosis is a potential intervention. Currently, there is no licensed EBV vaccine and, in order to progress the development of EBV vaccines for preventing MS, a greater understanding of the association of EBV with MS is required.

Congenital cytomegalovirus infection in pregnancy: a review of prevalence, clinical features, diagnosis and prevention

Human cytomegalovirus (CMV) is under-recognised, despite being the leading infectious cause of congenital malformation, affecting ~0.3% of Australian live births. Approximately 11% of infants born with congenital CMV infection are symptomatic, resulting in clinical manifestations, including jaundice, hepatosplenomegaly, petechiae, microcephaly, intrauterine growth restriction and death. Congenital CMV infection may cause severe long-term sequelae, including progressive sensorineural hearing loss and developmental delay in 40-58% of symptomatic neonates, and ~14% of initially asymptomatic infected neonates. Up to 50% of maternal CMV infections have nonspecific clinical manifestations, and most remain undetected unless specific serological testing is undertaken. The combination of serology tests for CMV-specific IgM, IgG and IgG avidity provide improved distinction between primary and secondary maternal infections. In pregnancies with confirmed primary maternal CMV infection, amniocentesis with CMV-PCR performed on amniotic fluid, undertaken after 21-22 weeks gestation, may determine whether maternofetal virus transmission has occurred. Ultrasound and, to a lesser extent, magnetic resonance imaging are valuable tools to assess fetal structural and growth abnormalities, although the absence of fetal abnormalities does not exclude fetal damage. Diagnosis of congenital CMV infection at birth or in the first 3 weeks of an infant's life is crucial, as this should prompt interventions for prevention of delayed-onset hearing loss and neurodevelopmental delay in affected infants. Prevention strategies should also target mothers because increased awareness and hygiene measures may reduce maternal infection. Recognition of the importance of CMV in pregnancy and in neonates is increasingly needed, particularly as therapeutic and preventive interventions expand for this serious problem.

Human herpes viruses in pregnancy: cytomegalovirus, Epstein-Barr virus, and varicella zoster virus

Viruses of the human herpesvirus family can have profound effects on pregnancy. Primary maternal infection with cytomegalovirus (CMV) and varicella during pregnancy has been associated with fetal abnormalities and neonatal disease. Public awareness of the role of cytomegalovirus in the etiology of developmental disorders and chronic disabilities needs to increase. With time, we may see new interventions for treatment of infected pregnant women and prevention of long-term effects. Attention must be focused on development of a safe and effective vaccine. With the introduction of an efficacious varicella vaccine, the rate of varicella in pregnancy is expected to decrease dramatically. Physicians caring for women have the opportunity to prevent the complications of varicella by identifying and vaccinating susceptible women.

A follow up study of cytomegalovirus infection in a group of Turkish renal transplant recipients using molecular assays

The clinical value of an in-house cytomegalovirus nested polymerase chain reaction (CMV-PCR) and a commercial molecular assay hybrid capture CMV DNA assay (HCA) was evaluated in monitoring a group of renal transplant patients for six months follow up. In this study, the sensitivity, specificity, positive predictive value, and negative predictive value of nested CMV DNA PCR assay and HCA at the beginning of the study were 70, 42.9, 46.7, 66.7, and 60, 78.6, 66.7, and 73.3% respectively. After six months, they were 80, 66.7, 80, 66.7 for CMV PCR and 73.3, 88.9, 91.7, 66.7% for HCA respectively. These results indicate that in monitoring and predicting CMV infections in renal transplant recipients, not only qualitative but also quantitative assays must be used together in order to decide the preemptive strategies.

The detection of CMV in amniotic fluid and cervicovaginal smear samples by real-time PCR assay in prenatal diagnosis

OBJECTIVE

There is no specific antiviral therapy or a vaccine, which could be safely administered to the pregnant women with primary human cytomegalovirus (CMV) infection. Therefore, prenatal diagnosis has a critical role in the management of pregnancy, complicated by this disease. In this study, we investigated the prevalence and clinical consequences of human CMV infection from cervicovaginal smear and amniotic fluid samples of pregnant women by using real-time polymerase chain reaction (RT-PCR) assay, in one of the Obstetrics and Gynecology outpatient clinics of Turkey. The identification of reliable prognostic markers of fetal disease remains the main purpose and a major challenge on this issue.

METHODS

Two hundred and six samples, of which 135 were cervicovaginal smear and 71 were amniotic fluid, were enrolled in the study. The DNAs of the samples were extracted by using Roche Diagnostic (Roche, Germany) kit and amplifications of these DNAs were studied by using Light-Cycler system (Roche Germany) as being quantitative. Anti-CMV IgM antibodies in the samples were studied by both MEIA (Imx system, Abbot Laboratories, USA) and a commercial ELISA kit (Radim SPA, Italy) while anti-CMV IgG antibodies were studied by MEIA (Axsym system, Abbot Laboratories, USA).

RESULTS

Human CMV DNA was found to be positive in 1.5% (2 in 135) of cervicovaginal smear and 1.4% (1 in 71) of amniotic fluid samples by RT-PCR. IgM and IgG were found to be negative in all of the cervicovaginal smear samples by both MEIA and ELISA, while IgG antibody was found to be positive in only one of the amniotic fluid samples by MEIA.

CONCLUSION

With RT-PCR assay, we have found the prevalence of human CMV in pregnant women similar to epidemiologic reports, which have been described earlier. Whereas the fetus with positive amniotic fluid in favor of human CMV had an intrauterine growth restriction resulted in intrauterine exitus, no symptoms were observed in the infants of the other two pregnant women with positive RT-PCR results. The fact that the clinical consequence of the newborn whose amniotic fluid evaluation revealed human CMV infection by RT-PCR made us think that this molecular diagnosis method may be a reliable assay in prenatal diagnosis of this pathogen.

Successful use of oral ganciclovir for the treatment of intrauterine cytomegalovirus infection in a renal allograft recipient

Congenital cytomegalovirus (CMV) infection occurs in approximately 1% of newborns and is the leading infectious cause of congenital birth defects. Female renal allograft recipients who develop CMV infection during pregnancy are at risk for both graft dysfunction and fetal morbidity. DNA-based analysis of amniotic fluid (AF) from at-risk pregnancies has been suggested as an adjunct/substitute for traditional culture. We have shown that CMV-polymerase chain reaction of AF is a useful diagnostic test for congenital CMV infection. Using this test we diagnosed CMV infection in the fetus of a 30-year-old renal transplant recipient. As termination was not an option for the family, the patient was extensively counseled and treated with oral ganciclovir. This resulted in clearance of the virus from the AF and the delivery of a healthy newborn girl, free of CMV disease. This is the first reported case to our knowledge of successful use of maternal ganciclovir to treat intrauterine CMV infection in a pregnant renal transplant recipient.

Requirements for diagnosis of prenatal cytomegalovirus infection by amniotic fluid culture

BACKGROUND

Amniotic fluid culture is considered to be the best method for the detection of antenatal cytomegalovirus (CMV) infection and prediction of congenital CMV infection. Recently, however, some false-negative results have been reported.

OBJECTIVES

Prediction of congenital CMV infection by amniotic fluid culture with emphasis on false-negative results.

STUDY DESIGN

Retrospective study of 42 pregnant women with primary CMV infection. First, estimation of seroconversion related to the gestational age was established. Afterwards, results of amniotic fluid culture were compared either with CMV isolation from biopsies from aborted fetuses, or with viral culture of newborns' urine.

RESULTS

In 18 cases (43%), amniotic fluid culture gave negative results which coincided with 18 uninfected newborns. In 18 other cases (43%), amniotic fluid culture was positive for CMV: 7 newborns with CMV viruria and 11 terminations of pregnancy with CMV isolated from fetal biopsies. In the remaining 6 cases, amniotic fluid culture gave negative results, whereas the 6 newborns were all infected.

CONCLUSION

Amniotic fluid culture remains an accurate method for the diagnosis of CMV antenatal infection. However, in order to avoid false-negative results, the importance of a correct estimation of the gestational age of seroconversion and of a sufficient interval between primary infection and amniocentesis are stressed.

Prenatal diagnosis of fetal growth restriction

Fetal growth restriction is one of the most challenging obstetric problems. Due to confusing terminology, there is an obvious lack of uniform diagnostic criteria. At present, most authors do not distinguish between the terms 'small for gestational age' (SGA) and 'intra-uterine growth restriction' (IUGR). These two clinical entities are not the same. The term 'SGA' should be used for an infant who has failed to achieve a weight threshold (usually defined as the 10th percentile). Conversely, an IUGR infant has, by definition, not reached his/her genetic growth potential due to an insult that has occurred in utero. An IUGR fetus may or may not be SGA but it always implies a pathological process. Clinicians tend to manage both conditions in the same way by delivering affected cases, often by elective Caesarean section and often prematurely. This strategy obviously represents an overtreatment. This chapter will discuss the various aetiologies of small fetuses and will provide the reader with diagnostic tools to distinguish between subtypes.

Real-time PCR quantification of human cytomegalovirus DNA in amniotic fluid samples from mothers with primary infection

A real-time PCR assay was developed to quantify human cytomegalovirus (HCMV) DNA in amniotic fluid (AF) samples collected from 30 pregnant women with primary HCMV infection as detected either from HCMV-immunoglobulin G (IgG) seroconversion or by the presence of HCMV-specific IgG and IgM associated with a low IgG avidity. Clinical information available for each case included ultrasonographic examination and fetal or newborn outcome. HCMV infection of fetuses or newborns was confirmed for the 30 studied cases. AF samples were subdivided into three groups. In group A (n = 13), fetuses presented major ultrasound abnormalities, and pregnancy was terminated. In group B (n = 13), fetuses had normal ultrasound findings, the pregnancy went to term, and the newborns were asymptomatic at birth. In group C (n = 4), fetuses had no or minor ultrasonographic signs, and pregnancy was terminated. The HCMV DNA load values in AF samples were significantly higher in group A (median, 2.8 x 10(5) genome equivalents [GE]/ml) than in group B (median, 8 x 10(3) GE/ml) (P = 0.014). Our findings suggest that HCMV load level in AF samples correlates with fetal clinical outcome but might also be dependent on other factors, such as the gestational age at the time of AF sampling and the time elapsed since maternal infection.

Prenatal diagnosis of congenital cytomegalovirus infection in 189 pregnancies with known outcome

Prenatal diagnosis (PD) of fetal cytomegalovirus (CMV) infection was performed in 242 pregnancies, with known outcome in 189 cases. In 141/189 pregnancies, PD was carried out on account of suspicious maternal CMV serology up to gestational week (WG) 23, and in 48 cases on account of abnormal ultrasonic findings detected between WG 18 and 39. Chorionic villus samples (n = 6), amniotic fluid (AF, n = 176) and/or fetal blood specimens (n = 80) were investigated for detection of virus by cell culture, shell vial assay, PCR and/or CMV-specific IgM antibodies. Of 189 fetuses correctly evaluated by CMV detection either in fetal tissue following therapeutic abortion/stillbirth (n = 24) or in urine of neonates within the first 2 weeks of life (n = 33), 57 were congenitally infected. In women with proven or suspected primary infection, the intrauterine transmission rates were 20.6% (7/34) and 24.4% (10/41), respectively. Of the congenitally infected live-born infants, 57.6% (19/33) had symptoms of varying degree. The overall sensitivity of PD in the serologic and ultrasound risk groups was 89.5% (51/57). A sensitivity of 100% was achieved by combining detection of CMV-DNA and CMV-specific IgM in fetal blood or by combined testing of AF and fetal blood for CMV-DNA or IgM antibodies. There was no instance of intrauterine death following the invasive procedure. The predictive value of PD for fetal infection was 95.7% (132/138) for negative results and 100% (51/51) for positive results. Correct results for congenital CMV infection by testing AF samples can be expected with samples obtained after WG 21 and after a time interval of at least 6 weeks between first diagnosis of maternal infection and PD. In case of negative findings in AF or fetal blood and the absence of ultrasound abnormalities at WG 22-23, fetal infection and neonatal disease could be excluded with high confidence. Positive findings for CMV infection in AF and/or fetal blood in combination with CMV suspicious ultrasound abnormalities predicted a high risk of cytomegalic inclusion disease (CID). Furthermore, detection of specific IgM antibodies in fetal blood was significantly correlated with severe outcome for the fetus or the newborn (p = 0.0224). However, normal ultrasound of infected fetuses at WG 22-23 can neither completely exclude an abnormal ultrasound at a later WG and the birth of a severely damaged child nor the birth of neonates which are afflicted by single manifestations at birth or later and of the kind which are not detectable by currently available ultrasonographic techniques.

Prenatal diagnosis of congenital cytomegalovirus infection

OBJECTIVE

To assess prospectively the diagnostic reliability and prognostic significance of prenatal diagnosis of cytomegalovirus (CMV) infection.

METHODS

One hundred ten pregnant women (four with twin pregnancies) with a risk of congenital CMV infection were investigated. Prenatal diagnosis was carried out by amniocentesis and fetal blood sampling (n = 75) or amniocentesis alone (n = 35). Serial ultrasonographic examinations were performed from time of referral until pregnancy end. All infected neonates were given long-term follow-up. Autopsy was performed in all cases of termination of pregnancy.

RESULTS

Nearly 23% (26 of 114) of fetuses were infected and prenatal diagnosis was positive in 20 cases. Sensitivity of prenatal diagnosis was 77% and specificity 100%. In eight cases, parents requested termination of pregnancy on the basis of abnormal ultrasonographic findings and/or biologic abnormalities in fetal blood. In 12 cases, parents decided to proceed with the pregnancy. In this group, one intrauterine and one neonatal death were observed. In one case, prenatal diagnosis revealed an abnormal cerebral sonography and the infant had bilateral hearing loss at birth. In 15 cases (nine positive and six false-negative prenatal diagnoses), no apparent lesion was present at birth, nor did it develop during the follow-up period (mean 31 months). In 88 (77.2%) of 114 infants, no evidence of vertical transmission was found during the pre- or postnatal period.

CONCLUSION

Prenatal diagnosis provides the optimal means for both diagnosing fetal infection (amniocentesis) and identifying fetuses at risk of severe sequelae (ultrasound examination, fetal blood sampling), thus allowing proper counseling.

Congenital and perinatal infections with cytomegalovirus

Congenital cytomegalovirus (CMV) infections remain the leading viral cause of congenital malformations in the developed world. Despite advances in our knowledge, the epidemiology and natural history of congenital CMV infection are still poorly understood, particularly in Australia. Congenital CMV causes illness ranging from no clinical disease (asymptomatic, but infected) through to prematurity, encephalitis, deafness and haematological disorders and death. Perinatal CMV acquisition usually results in less severe illness including asymptomatic infection, acute infection with hepatitis, fever, and pneumonitis. CMV infects only humans, and in vitro and in vivo models for intrauterine infection are required in order to test new treatments, and better describe the pathogenesis of congenital CMV. Using new knowledge of the epidemiology and natural history of CMV, treatment regimens during late pregnancy are currently undergoing clinical trial although no definitive recommendations are available.

Congenital HCMV infection: a collaborative and comparative study of virus detection in amniotic fluid by culture and by PCR

Cytomegalovirus (HCMV) infection is the leading cause of congenital virus infection in developed countries, affecting an estimated 1% of births. This antenatal infection can cause serious sequelae. Strategies for prevention and treatment must, therefore, be agreed upon, entailing a preliminary performance assessment of antenatal virus diagnosis techniques. Between 1992 and 1999, HCMV serology status was established for 19456 pregnant women in four French hospitals. Seronegative patients (55.4%) were given serology screening, and antenatal diagnosis was given to 152 women who had shown seroconversion during their pregnancies (1.4%). The detection of HCMV transmission from mother to fetus was finally established in 95 cases, using polymerase chain reaction (PCR) and viral culture methods for detecting HCMV in the amniotic fluid. These results were compared with viral culture of children's urine after birth, enabling us to distinguish between children really infected in utero (30%) and non-infected children (70%). The results of the virus culture and those of PCR were identical in 94 of the 95 cases, with one discrepancy (culture-/PCR+). The two diagnosis techniques had identical sensitivity (72%), with culture proving slightly more specific than PCR (98.4% as opposed to 96.9%). Positive prediction values for culture and for PCR were, respectively, 95.6 and 91.3%. Antenatal virus diagnosis on amniotic fluid was negative with both techniques in 8 out of 29 cases of children born with HCMV infection (VPN=89%). Over half of these wrongly negative results can be explained by amniocentesis carried out too early in the pregnancy or too early with respect to the mother's primary infection.

Development and application of a PCR-based method including an internal control for diagnosis of congenital cytomegalovirus infection

Cytomegalovirus (CMV) is the most common cause of congenital infection in the developed world. We have designed and evaluated an assay that includes an internal control for amplification and detection of CMV DNA in amniotic fluid and neonatal urine samples. We present data on the use of this assay in the diagnosis of congenital CMV infection. A total of 145 amniotic and fetal fluid samples were examined by this assay; 83 were from healthy pregnant women and 62 were from women who were being investigated because of concerns over the pregnancy (diagnostic group). CMV DNA was detected in three amniotic fluid samples from the diagnostic group but was not detected in any samples taken from healthy pregnant women. Thirty-nine urine samples were obtained from 19 neonates with suspected congenital infection; CMV DNA was detected in urine from 6 of these patients. The assay provides useful information about CMV infection in the fetus and the neonate; when used in conjunction with other diagnostic tools it will enable mothers and obstetricians to make informed decisions about the management of pregnancies complicated by CMV infection.

Prevalence of maternal cytomegalovirus (CMV) antibody and detection of CMV DNA in amniotic fluid

The prevalence of cytomegalovirus (CMV) IgG antibody was determined in 573 pregnant women in the first trimester. The overall prevalence of CMV IgG antibody was 77.5%. The rate of seropositivity was 67.7% in women < 25 yr, and increased with age to 85.7% in women 40 yr. These results imply that young women in Japan are at increased risk for primary CMV infection during pregnancy and that congenital CMV infection rates might increase in the future. We conducted a prospective study of 75 pregnant women who underwent amniocentesis for various indications to determine if CMV DNA could be detected in the amniotic fluid. None had symptoms associated with CMV infection, CMV IgM antibody, or seroconversion to CMV IgG antibody during pregnancy. CMV DNA was not detected in the amniotic fluid using a polymerase chain reaction assay. The 65 fetuses, including 3 sets of twins, were followed through birth. CMV DNA was not detected in urine samples obtained within the first 2 weeks of life. In conclusion, CMV DNA was not detected in the amniotic fluid of women who did not have CMV infection. These results, however, suggest that the negative predictive value of prenatal amniotic fluid analysis is high and that the presence of CMV DNA in the amniotic fluid has clinical significance for the diagnosis of congenital CMV infection if detected in pregnant women.

Prenatal diagnosis of human cytomegalovirus by culture and polymerase chain reaction: 98 pregnancies leading to congenital infection

Human cytomegalovirus (HCMV) is the most common cause of viral intra-uterine infection. The experience with prenatal diagnosis remains limited and is based on few reports of small numbers of cases. It is thus difficult to compare the accuracy of the different tests because the groups studied were small and heterogeneous. We describe here our experience on a series of 98 pregnancies leading to HCMV congenital infection, among which 71 have been tested by amniotic fluid (AF) sampling followed by culture and/or polymerase chain reaction (PCR). Independently of the delay between AF sampling and the first HCMV IgM positive result, the mean sensitivity of both culture and PCR was around 70 per cent. The best sensitivity (95.5 per cent) was obtained after a delay > or = 6 weeks in late pregnancy (> or = 23 weeks). The present study demonstrated clearly that the delay between AF puncture and the presumed date of seroconversion is more important for sensitivity than the technique used for the diagnosis (PCR or culture). However, even in the best diagnostic conditions, negative results of HCMV culture or PCR in AF cannot formally exclude intra-uterine infection.

Prenatal diagnosis of congenital cytomegalovirus infection

We report here the results of a study on the prenatal diagnosis of congenital cytomegalovirus (CMV) infection. The study was carried out by both PCR and virus isolation from amniotic fluid (AF) for 82 pregnant women at risk of transmitting CMV for the detection of (i) seroconversion to CMV immunoglobulin G (IgG) positivity during the first trimester of pregnancy, (ii) symptomatic CMV infection in the mother during the first trimester of pregnancy or intrauterine growth retardation detected by ultrasound or abnormal ultrasonographic findings suggestive of fetal infections, and (iii) seropositivity for CMV-specific IgM. For 50 women, fetal blood (FB) was also obtained and tests for antigenemia and PCR were performed. The results indicate that AF is better than FB for the prenatal diagnosis of CMV infection. PCR with AF has a sensitivity (SNS) of 100%, a specificity (SPE) of 83.3%, a positive predictive value (PPV) of 40%, and a negative predictive value (NPV) of 100%; rapid virus isolation with the same material has an SNS of 50%, an SPE of 100%, a PPV of 100%, and an NPV of 94.7%. Fewer than 10% of the women positive for IgM by enzyme immunoassay (EIA) had a congenitally infected fetus or newborn infant. When EIA IgM positivity was confirmed by Western blotting (WB) and the WB profile was considered, the percent transmission detected among women with an "at-risk" profile was higher than that observed among IgM-positive women and was the same as that among women who seroconverted during the first trimester of pregnancy (transmission rates of 29 and 25%, respectively).

Improved prenatal diagnosis of congenital human cytomegalovirus infection by a modified nested polymerase chain reaction

Two major variables may cause false-negative results in prenatal diagnosis of congenital human cytomegalovirus (HCMV) infection: sensitivity of the techniques(s) used; and time elapsed between maternal infection and antenatal testing. Previous results indicated that rapid HCMV isolation from amniotic fluid samples and viral DNA detection in amniotic fluid by nested polymerase chain reaction (nPCR) had comparable levels of sensitivity (69.2% and 76.9%, respectively). The nPCR protocol was reviewed following two additional false-negative antenatal diagnosis in a twin pregnancy during which two procedures were performed at 18 and 23 weeks of gestation, respectively. In the new assay, multiple (instead of single) and 100 (instead of 20) microliters amniotic fluid aliquots were individually amplified and tested by nPCR. By using this approach, low DNA levels (1-10 genome equivalents) were detected in 1-5/8 replicates of amniotic fluid samples taken from both twins during both procedures. In addition, viral DNA was detected in 5/6 replicates from two amniotic fluid samples still available from two previous false-negative cases. However, nPCR on multiple amniotic fluid replicates did not anticipate positive prenatal results in a retrospective case, which required two procedures for correct diagnosis and, when prospectively employed, did not avoid one additional false-negative prenatal diagnosis 8 weeks after maternal infection. Thus, delayed intrauterine transmission of the infection may be a potential cause of false-negative results. However, the combination of a very sensitive technique with appropriate timing of prenatal testing can substantially increase the reliability of prenatal diagnosis results.

Perinatal herpesvirus infections. Herpes simplex, varicella, and cytomegalovirus

The herpesvirus infections (herpes simplex, varicella, and cytomegalovirus) create many dilemmas when encountered during pregnancy. This article reviews the epidemiologic diagnosis and management of perinatal herpesvirus infections. A review of possible future trends is also included.

Evaluation of virological procedures to detect fetal human cytomegalovirus infection: avidity of IgG antibodies, virus detection in amniotic fluid and maternal serum

Human cytomegalovirus (HCMV) is the most common cause of viral intrauterine infection and fetal damage largely due to maternal primary infection. Virological procedures which are able to detect HCMV fetal infection were evaluated. HCMV IgG antibodies were detected in 62.5% of the pregnant women and 1.47% had a primary infection. From March, 1992 to August, 1995, 29 seroconversions were observed, and in 64 other cases. HCMV IgM antibodies were detected in the first serological test. The mean IgG antibody avidity test (AI) was 31% for the 11 seroconversions tested and 74% in 32 cases where IgG and IgM HCMV antibodies were detected in the first serum. In the 29 HCMV seroconversions, 19 amniocentesis were carried out and 12 fetuses (41.4%) were infected in utero. In four amniotic fluids positive in culture and PCR, the fetus or newborns were infected and in one out of the two cordocentesis undertaken, hepatitis, anemia, and thrombocytopenia were noted. In four other cases, investigations seeking HCMV in amniotic fluid were negative whereas infants were infected at birth. Among the 64 cases with positive HCMV IgM and IgG antibodies detected in the first serological test, three fetuses were infected in utero, but no amniotic fluid was available in these cases. Amniotic fluids were studied in 39 cases, and HCMV detection by culture and PCR-hybridization was negative. HCMV DNA was detected in the maternal sera of five out of 21 pairs of seroconversions and in two cases on the first negative serum. The assay was also carried out on 50 of the 64 HCMV IgM positive sera. Two had detectable HCMV DNA.

Infection materno-foetale à cytomégalovirus

Congenital cytomegalovirus infection is frequent. Symptomatic disease at birth is infrequent but very severe. In most cases the infection is totally asymptomatic but neurosensorial damage can occur in 10 % to 15 % of children, hearing loss being the most frequent. Maternal or neonatal screening is the only way to recognise asymptomatic disease. Wether the screening has to be done, and if so when, will be discussed here.

Polymerase chain reaction for prenatal diagnosis of congenital human cytomegalovirus infection

The reliability of the polymerase chain reaction (PCR) for prenatal diagnosis of human cytomegalovirus (HCMV) infection was determined by retrospective testing of 35 amniotic fluids identified previously as positive or negative for HCMV by virus isolation. Amniocentesis was performed in 26 pregnant women with primary HCMV infection at 14-36 weeks gestation, 3-21 weeks after maternal infection. Blood samples were obtained from 20 fetuses for IgM determination and/or virus isolation. Amniotic fluid culture led to antenatal diagnosis of HCMV in 9 of the 13 infected fetuses (sensitivity 69.2%) with one case diagnosed at a second sampling. PCR was able to detect one additional infected fetus (10/13, sensitivity 76.9%). Nested PCR did not increase sensitivity of prenatal diagnosis. Three cases were not diagnosed by all the techniques employed. The specificity of virus isolation from and DNA detection by PCR in amniotic fluid was 100%. The negative predictive value for virus isolation from amniotic fluid was 76.5% and for DNA detection by PCR 81.2%, whereas the positive predictive value was 100% for both techniques. The results showed that neither approach can detect all cases of congenital HCMV infection prenatally, and that the time interval between maternal infection and sampling seems to be a major factor affecting the reliability of prenatal diagnosis.

Accuracy of amniotic fluid testing before 21 weeks' gestation in prenatal diagnosis of congenital cytomegalovirus infection

Cytomegalovirus (CMV) is the most common cause of intrauterine infection. Recent publications show amniocentesis to have an 81-100 per cent sensitivity in antenatal diagnosis after 21 weeks' gestation. Testing before 21 weeks' gestation is less well documented. We performed 36 amniocenteses between 14 and 20 weeks' gestation. The sensitivity was 45 per cent and the specificity 100 per cent. Implications and possible causes of this low sensitivity are discussed.