Update on the prevention, diagnosis and management of cytomegalovirus infection during pregnancy

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1. Update on the prevention, diagnosis and management of
cytomegalovirus infection during pregnancy
T. Lazzarotto
1
, B. Guerra
2
, L. Gabrielli
1
, M. Lanari
3
and M. P. Landini
1
1)Department of Haematology, Oncology and Laboratory Medicine, Operative Unit of Clinical Microbiology,2)Department of Obstetrics and Gynaecology,
St Orsola Malpighi General Hospital, University of Bologna, Bologna and3)Operative Unit of Paediatrics and Neonatology, La Scaletta Hospital,
Imola-Bologna, Italy
Abstract
Human cytomegalovirus (CMV) is the leading cause of congenital infection, with morbidity and mortality at birth and sequelae. Each year
approximately 1–7% (Rev Med Virol 2010; 20: 311) of pregnant women acquire a primary CMV infection. Of these, about 30–40% trans-
mit infection to their fetuses. The risk of serious fetal injury is greatest when maternal infection develops in the first trimester or early
in the second trimester. Between 10 and 15% of congenitally infected infants are acutely symptomatic at birth and most of the survivors
have serious long-term complications. Until a few years ago, laboratory testing was not possible to precisely define the maternal
immune status, the recent development of advanced serological tests (IgG avidity test, IgM immunoblot and neutralizing antibody test-
ing) allow us to identify, among pregnant women with suspected CMV, those with primary infection who are therefore at high risk of
transmitting CMV to the fetus. This is done with the use of a screening test. As most maternal infections are asymptomatic, the only
way to disclose primary infection is to implement specific serological testing as early in pregnancy as possible (before week 12–16 of
gestation). Given the high risk of mother–fetus transmission and fetal damage, prenatal diagnosis is recommended to women with pri-
mary CMV infection contracted in the first half of pregnancy and in case of fetal abnormalities suggestive of infection. The correct inter-
pretation of serological and virological tests followed by appropriate counselling by an expert physician is an effective tool to reduce
the number of unnecessary pregnancy terminations by over 70% (Am J Obstet Gynecol2007; 196: 221.e1).
Keywords:Amniocentesis, cytomegalovirus, pregnancy, prevention, serological diagnosis
Article published online:25 April 2011
Clin Microbiol Infect2011;17:1285–1293
Corresponding author:T. Lazzarotto, Department of Haemato-
logy, Oncology and Laboratory Medicine, Operative Unit of Clinical
Microbiology, Laboratory of Virology, Policlinico S. Orsola Malpighi,
Via Massarenti n. 9, 40138 Bologna, Italy
E-mail: [email protected]
Introduction
Human cytomegalovirus (CMV) is an endemic and ubiquitous
beta-herpesvirus that leads to congenital infection in 0.3–
2.3% of all live births [1,2]. The overall birth prevalence of
congenital CMV infection was reported to be 0.64% (95% CI
0.60–0.69), but varied considerably among different study
populations [3].
Congenital CMV infection is the leading non-genetic cause
of deafness in children: more than half of babies born with
symptomatic infection and 10% of asymptomatic newborns
will develop mild to severe neurosensory hearing loss, which
is progressive in 50% of cases [4].
Infection with CMV can occur in pregnant women by
non-primary infection, namely reactivation of the latent
virus or reinfection with a different strain, or by primary
infection.
Mother–child transmission is mainly the result of primary
maternal CMV infection, which carries a risk of transmission
varying from 14.2% to 52.4% (combined prevalence 32.4%)
[3], the transmission rate is lower, 36%, during the first
ª2011 The Authors
Clinical Microbiology and Infectionª2011 European Society of Clinical Microbiology and Infectious Diseases
REVIEW 10.1111/j.1469-0691.2011.03564.x

2. trimester compared with third-trimester infection, 77.6% [5].
Cases of CMV transmission as the result of non-primary
infection have been reported in 1.4% (1.1–1.7%) of cases, i.e.
at a much lower rate than those resulting from primary
infection [3].
The extent of fetal/newborn injury, namely severe brain
damage, is correlated to the gestational epoch in which verti-
cal transmission occurs: the most severe is correlated to pri-
mary maternal infection contracted in the first 2 months of
pregnancy [6].
Only 10–15% of congenitally infected babies present
symptoms of infection at birth and these infants have a
perinatal mortality rate of around 10% with 70–80% of sur-
viving babies presenting major neurological sequelae [7].
The prognosis of symptomatic infants is very poor, with the
majority suffering from severe mental impairment and/or
hearing loss. Despite infection, 85–90% of babies have no
symptoms at birth but 8–15% of them will suffer delayed
injury [2,7].
Cytomegalovirus can also be transmitted to the fetus
when primary maternal infection occurs before conception.
In 2006 Revelloet al.[8] reported that preconception pri-
mary CMV infection (3 months before the last menstrual
period) carries a low risk of intrauterine transmission (8.7%)
and one of 12 newborns examined at birth was found to be
subclinically infected. In another study, Daimingeret al.[9]
reported no cases of intrauterine transmission in three
women in whom primary CMV infection occurred 2–
8 weeks before their last menstrual period. The risk of intra-
uterine transmission after preconceptional primary CMV
infection appears to be significantly lower than that associ-
ated with primary infection during pregnancy.
The transmission rate is considerably higher in the case
of periconceptional CMV infection. Revelloet al.[10]
showed that in periconceptional infection (4 weeks after
the last menstrual period) the virus was transmitted in
30.8% of cases. Daimingeret al.[9] reported a 45% trans-
mission rate of CMV infection in the periconceptional per-
iod (between 1 week before and 5 weeks after last
menstrual period) and recently, Hadaret al.[11] found a
vertical transmission rate of 25% in primary periconcep-
tional CMV infection (4 weeks before last menstrual period
and up to 3 weeks after the expected date of the missed
menstrual period). The outcome of periconceptional infec-
tion with regard to symptomatic disease in the fetus or
newborn was difficult to assess.
Prospective studies designed to investigate the transmis-
sion rate and outcome in women with preconceptional and
periconceptional primary CMV infection are needed.
Prevention
It is well known that primary infections in the mother have a
much greater clinical impact on the fetus than reactivated
infections or exogenous reinfections [12]. Prevention is diffi-
cult because the virus is ubiquitous and infection is common.
Screening
No country performs systematic screening for CMV infection
among pregnant women as universal screening for CMV pri-
mary infection. The time for screening would be at the
beginning of pregnancy. Arguments against screening include
the fact there is no effective vaccine and no treatment that
has been proven effective. Nevertheless, in certain areas, lar-
gely uncontrolled serological screening is increasingly per-
formed with the objective of prenatal diagnosis.
Hygienic intervention
Although controversial, there are some practices that might
minimize the risk for congenital infection. The saliva and
urine of infected children are significant sources of CMV
infection among women who are pregnant. Prevention
behaviours (i.e. hand washing whenever there is contact
with a child’s saliva or urine, not sharing drinking glasses
or eating utensils with young children, and not kissing
young children on the mouth or cheek) appear to be gen-
erally acceptable.
Education of pregnant women about the implication of
acquiring CMV infection is vital. In a study where seronega-
tive mothers with a child in group day care were instructed
on measures to prevent CMV transmission, pregnant moth-
ers had a significantly lower rate of CMV infection when
compared with non-pregnant mothers attempting conception
[13]. Recently, Vauloup-Fellouset al. [14] reported that
hygiene counselling given during pregnancy reduces the CMV
seroconversion rate.
Hygienic intervention for CMV-seronegative pregnant
women in both Europe and the United States is now appro-
priate.
Active vaccine
The development of a CMV vaccine is one of the highest
health priorities, but availability of a licensed vaccine to pre-
vent CMV infection in seronegative individuals is not immi-
nent. In 2009, Passet al.published the first results of a phase
2, randomized, double-blind, placebo-controlled clinical trial
of vaccine consisting of recombinant CMV envelope glyco-
protein B with MF59 adjuvant. The authors conclude that
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Clinical Microbiology and Infectionª2011 European Society of Clinical Microbiology and Infectious Diseases,CMI,17, 1285–1293

3. CMV glycoprotein B vaccine has the potential to decrease
incident cases of maternal and congenital CMV infection but
future studies, such as a phase 3 clinical trial, are needed to
confirm the efficacy of this vaccine [15].
Prenatal treatment
Currently, no therapeutic options during pregnancy are avail-
able except for clinical trials. Recent data in the literature
have focused on the efficacy of preventive administration of
CMV immunoglobulins [16] or antiviral drugs (valacyclovir)
[17] to pregnant women with primary CMV infection to
reduce the rate of vertical transmission and improve neona-
tal outcome.
The first multicentre study (CHIP study: Congenital HCMV
Infection Prevention—Clinical Trials.gov ID NCT00881517)
was designed as a randomized, double-blind, placebo-con-
trolled, prospective trial (phase 2) for the evaluation of the effi-
cacy of CMV-specific hyperimmune globulin Cytotect

,
(Biotest AG, Dreieich, Germany) administration in pregnant
women with the acute phase of primary CMV infection for pre-
vention of intrauterine transmission. This experimental study
began in February 2010 in Italy, enrolment ended in March
2011 and the study will be completed in December 2011.
A second multicentre study (Cytotect

study) was
designed as a phase 3 prospective trial in congenital CMV
infection for the evaluation of the efficacy of CMV-specific
hyperimmune globulin Cytotect

, (Biotest AG) administered
in pregnant women who seroconverted in the first trimester
to protect against transmission of the virus to the unborn
child and thereby to prevent injury to the child. This experi-
mental study began in 2008 in Germany. In January 2011 the
interim analysis showed an indication of the efficacy of Cyto-
tect

when the treatment group was compared with the
control group. The interim analysis was conducted on 7000
of the 30 000 pregnant women planned to complete the
study (http://www.biotest.de/ww/en/pub/investor_relations/
news/newsdetails.cfm?newsID=1025191).
A third multicentre study (http://joomla.ikrconsulting.com/
index.php?option=com_content&view=article&id=45&Itemid=
57) was designed as a randomized double-blind placebo-con-
trolled prospective trial evaluating the efficacy of valacyclovir
(the oral pro-drug of acyclovir), The drug is given orally to
pregnant women in cases of confirmed fetal CMV infection
(amniotic fluid PCR-positive) and with extracerebral signs
visible on ultrasound that can be attributed to the infection
to reduce the number of cases with unfavourable outcomes
(children symptomatic at birth) and of medically indicated
terminations of pregnancy. This experimental study began in
September 2009 in France and the study will be completed
in June 2013.
Diagnosis of Maternal Infection
Today, laboratory techniques represent a decisive approach
for diagnosis of CMV infection in pregnancy.
Clinical findings
Most CMV infections encountered in pregnant women are
asymptomatic even during the acute stage. About 25% of
pregnant women with primary infection are reported to be
symptomatic. Even in cases with symptoms, the manifesta-
tions are non-specific and mild, such as persistent low fever
(60.2% of cases), fatigue (48.8%) and headache (26.5%) [18].
Laboratory tests may sometimes disclose atypical lymphocy-
tosis and slightly raised transaminase levels. Clinical diagnosis
of CMV infection is unreliable.
Serological findings
The gold standard of serological diagnosis of primary CMV
infection is maternal seroconversion or the presence of
serum anti-CMV specific IgM antibodies combined with low
avidity anti-CMV IgG antibodies.
The diagnosis of primary CMV infection is straightforward
if seroconversion to CMV-specific antibodies, i.e. thede novo
appearance of virus-specific antibodies in the serum of a
pregnant woman who was previously seronegative, is
detected. In fact, if consecutive blood samples are available,
the presence of anti-CMV IgM and IgG antibodies in a previ-
ously IgG-negative individual provides determination of sero-
conversion and CMV primary infection.
Currently, routine antenatal screening for CMV of preg-
nant women has never been recommended by any public
health authority in any country so diagnosis via seroconver-
sion is only occasionally achieved.
Testing for anti-CMV IgM antibodies is the most widely
used and appropriate procedure for screening pregnant
women [19]. Anti-CMV IgM antibodies are a good indicator
of acute or recent infection but are not always correlated
with primary infection. This is because pregnant women can
produce IgM during reactivations or reinfections. In addition,
virus-specific IgM may persist for months after natural infec-
tion and anti-CMV IgM antibodies have been detected in
some pregnant women 6–9 months after the end of the
acute phase of primary infection. False-positive results are
common and may arise in patients with other viral infections
(e.g. parvovirus B19, Epstein–Barr virus) or autoimmune dis-
eases or as the result of interference by rheumatoid factor
of the IgM class, and finally false-positive results may also be
ascribed to the laboratory methods used [19–21]. Hence,
the detection of IgM in the serum of pregnant women may
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4. simply be a starting point for further diagnostic investigations
[22].
Immunoblotting with purified native viral proteins and
purified recombinant proteins (structural and non-structural)
has been shown to be an effective method to confirm the
presence of CMV IgM antibodies in serum with a high sensi-
tivity (100%) and specificity (98.6%) [23]. In addition, analysis
of the virus-specific IgM response to individual structural and
non-structural CMV proteins allows the detection of fairly
typical reactive profiles to distinguish primary from non-
primary infection. Moreover, serum IgM from women who
transmit CMV infection reacts with a higher number of anti-
gen bands than serum IgM from women who do not transmit
the infection, probably because transmitting women have a
higher viral load. (p <0.0001) [23].
The anti-CMV IgG avidity test is currently the most reli-
able commercial procedure to identify primary infection in
pregnant women [24]. Antibody avidity indicates the strength
with which a multivalent antibody binds to a multivalent anti-
gen. During the first weeks following primary infection, IgG
antibodies show a low avidity for the antigen, but they pro-
gressively and slowly mature, initially acquiring a moderate
and then a high avidity. This process reflects the maturation
of the immune response and the high avidity antibodies are
maintained for many years. For this reason, low avidity
CMV-IgG antibodies are found only after primary antigenic
stimulation and usually last for approximately 16–18 weeks
after the onset of CMV infection [25,26].
A low avidity index indicates the presence of low-avidity
IgG antibodies in serum during an acute or recent primary
CMV infection [27,28]. A high avidity index during the first
12–16 weeks of gestation could be considered a good indica-
tor of past infection [29].
The determination of anti CMV antibody avidity carried out
before weeks 12–16 of gestation is therefore a helpful tool to
identify all pregnant women who may give birth to an infected
newborn (100% sensitivity). If the IgG avidity index is deter-
mined later during pregnancy (after 18–20 weeks of gestation),
the sensitivity is drastically reduced (62.5%) [25].
Interpreting test results is important because serological
tests vary from one laboratory to another so the method
used and its reference values must be carefully assessed.
The value of CMV IgG avidity helps to interpret a positive
result for CMV IgM; the limits are that the kinetics of IgG
avidity depend on the kit used and with some of these
kits, the results may depend on CMV IgG concentration
[30,31].
Recently, Revelloet al.[30] reported the results of a com-
parative evaluation of eight Conformite´Europe´enne-marked
CMV IgG avidity assays and concluded that commercial kit
performances for IgG avidity determination are variable. In
this study the time frames chosen for the disaggregation in
three groups (<3 months, 3–6 months, >6 months) do not
allow a sound estimate of assay accuracy. The conclusions
obtained on this panel may then be difficult to translate in
practice and to compare with the results of previous studies
and with the package inserts of commercial CMV IgG avidity
assays.
Moreover, dating the infection may be difficult in cases for
which the IgG avidity index is reported as moderate/interme-
diate/grey-zone. Particular problems arise with large ranges
of reference values of moderate avidity because the larger
the range, the less specific the results are.
In our experience using the Radim CMV IgG avidity assay
(Cytomegalovirus IgG avidity EIA WELL; RADIM, Rome,
Italy), moderate avidity results combined with specific CMV-
IgM antibodies constitute a reliable marker of a recent pri-
mary infection especially when pregnant women are
screened for CMV infection for the first time only after the
first trimester and in the absence of previous serological data
[22]. We tested 380 sera that were positive for CMV IgG
and IgM collected from 380 pregnant women with ascer-
tained primary CMV infections. Pregnant women were ran-
domized into three groups. In the first group the primary
CMV infection was diagnosed before 12 weeks of gestation
and among the 99 pregnant women of this group, 70 had a
low avidity and 29 a moderate avidity for CMV IgG, with 16
of the 70 (23%) and one of the 29 (3.4%) transmitting a con-
genital CMV infection to the newborn/fetus. In the second
group, 240 primary CMV infections were diagnosed between
13 and 24 weeks of gestation: 180 of 240 pregnant women
had a low avidity and 60 had a moderate IgG avidity index,
with 57 of 180 (31.6%) and 14 of 60 (23.3%) transmitting
congenital CMV infection to the newborn/fetus. Similar data
were obtained in the third group, in whom the diagnosis of
primary CMV infection was established after 24 weeks of
gestation (T. Lazzarotto, unpublished data).
Today, we believe that moderate CMV IgG avidity must
be interpreted with caution and additional studies with other
commercial CMV IgG avidity assays are urgently needed to
understand the significance of IgG moderate/intermediate/
grey-zone avidity in confirming the diagnosis of CMV primary
infection during pregnancy.
In 2004 Mace´et al.[24] demonstrated that the best algo-
rithm for the diagnosis of primary CMV infection in pregnant
women was the determination of the anti-CMV antibody
avidity only in serum samples positive for IgM antibodies.
This procedure eliminates a number of samples with moder-
ate avidity index and IgM-negative results, which are difficult
tomanage
clinically.
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Clinical Microbiology and Infectionª2011 European Society of Clinical Microbiology and Infectious Diseases,CMI,17, 1285–1293

5. The CMV microneutralization assay carried out early in
pregnancy can identify all pregnant women who will transmit
CMV to their offspring [32]. After seroconversion the first
neutralizing titres appear after an average of 15 weeks (range
10–17 weeks), with a progressively increasing titre. The
absence of neutralizing antibodies in a serum sample from a
pregnant woman containing CMV IgG and IgM may indeed
provide additional evidence of recent primary infection [32].
Eggerset al.[32] showed that the combined application of
the microneutralization assay and avidity assay identified all
primarily infected pregnant women who gave birth to con-
genitally infected infants. Serological diagnosis of primary
CMV infection is then reliable.
In pregnant women who are CMV seropositive before
pregnancy the serological diagnosis of a non-primary CMV
infection may be documented by a significant increase in
CMV-specific IgG antibody titre with or without the presence
of specific IgM antibodies and high IgG avidity. It is recom-
mended that the consecutive blood samples be processed in
the same run to avoid analytical variability. In women whose
pre-pregnancy serological status is unknown the presence of
high titres of serum-specific IgG and IgM anti-CMV combined
with high IgG avidity during the first 12–16 weeks of gesta-
tion may be indicative of a non-primary CMV infection.
To date, serological diagnosis of non-primary CMV infec-
tion is difficult and often unreliable because no optimal diag-
nostic methods are available.
Virological findings
Virological tests play a secondary role in the diagnosis of pri-
mary CMV infection in pregnant women and can only sup-
port serological diagnosis [22].
Cytomegalovirus may or may not be detected in maternal
blood (DNAemia) in pregnant women undergoing primary
infection at the time of serological diagnosis. However, posi-
tive detection of virus in blood is not associated with a
greater risk of infection or fetal/neonatal injury [22]. In most
women with non-primary infection, DNAemia is negative.
In pregnancy, during both primary and non-primary infection,
CMV may be cleared in body fluids. Isolation of virus in urine or
cervical secretions is a poor indicator of the risk of intrauterine
transmission and the severity of fetal/neonatal damage. Virolog-
ical diagnosis of CMV infection is often unreliable.
Management of CMV Infection During
Pregnancy
As pregnancy does not usually affect the clinical course of
infection, which is usually symptom-free in immmunocompe-
tent subjects, laboratory tests are the best means of estab-
lishing diagnosis. It is up to the physician to decide on the
basis of maternal status before conception whether to test
for CMV in pregnancy and which tests to prescribe and then
to interpret the results accurately.
Women seropositive for CMV before conception
IgG-specific antibodies in serum disclosed at the first test
during pregnancy (week 8–10) is indicative of past infec-
tion and no further investigation is required. There is tacit
agreement among the international community that no lab-
oratory testing for CMV is needed, unless indicated by
particular clinical conditions such as abnormal ultrasono-
graphic findings. Even though it does not offer full protec-
tion, acquired immunity will defend the mother from
primary infection in pregnancy which carries a much
greater risk of fetal damage. Any reinfection or reactiva-
tion of infection carries the same risk as pregnancy itself.
For these reasons, the information on maternal status
before conception precludes the need for screening during
pregnancy [33].
Women seronegative for CMV before conception
Non-immune pregnant women at the early prenatal visit
(week 8–10) are at risk of acquiring primary infection. First
and foremost they must be informed of hygiene and behav-
iour measures (avoiding direct contact with organic materi-
als, close contact with pre-school children and frequent
thorough hand-washing) to reduce the chance of infection
[13]. Women with daily household or occupational contact
with children <3 years old are at high-risk of acquiring pri-
mary CMV infection during pregnancy.
Recommendations to prevent CMV infection during preg-
nancy have been edited by the European Congenital CMV
Initiative (ECCI; http://www.ecci.ac.uk/) and the Centers for
Disease Control and Prevention (CDC; http://www.cdc.gov/
cmv/index.html).
Seronegative pregnant women must also undergo peri-
odic serological testing. Although there are no universally
accepted guidelines, a second testing should be done at
15–16 weeks of pregnancy and no later than is reasonable
to implement fetal investigations in the case of serocon-
version. A positive result allows for the optimal timing of
prenatal diagnosis (20–21 weeks of gestation) considering
the time limit for termination of pregnancy in several
countries [34].
If the mother continues to be seronegative, serological fol-
low-up testing can be limited or confined to one more test
at 35–37 weeks to select newborns at risk of congenital
infection in the case of late seroconversion.
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6. Women whose pre-pregnancy serological status is unknown
Diagnosis of CMV infection is more complex in women who
are unaware of their serological status before pregnancy. As
most infections are asymptomatic, the only way to disclose
primary infection is to implement specific serological testing
as early in pregnancy as possible (before week 12–16 of ges-
tation). Recommendations for management of CMV infection
during pregnancy are shown inFig.1.
Diagnosis of Fetal Infection
Prenatal diagnosis
The fetal compartment can be studied by invasive and non-
invasive prenatal diagnostic investigation. Ultrasound has the
advantage of not being invasive and will disclose any struc-
tural or growth abnormalities caused by CMV infection, but
its sensitivity is poor and it correctly identifies no more than
20% of infected babies, even in a selected population [35,36].
In addition, a structural abnormality may be disclosed a long
time after the initial negative tests and borderline structural
changes detected early in pregnancy could be temporary
[35,36]. Moreover, when fetal infection status is unknown,
ultrasound abnormalities predict symptomatic congenital
infection in only a third of cases [35].
The diagnostic protocol, both invasive (amniocentesis or
cordocentesis) and non-invasive (ultrasonography) prenatal
diagnostic tests, has to be offered to women at high risk of
transmitting CMV to the fetus, in particular to pregnant
women who develop a primary infection or an undeter-
mined type of infection during the first half of gestation and
in case of abnormal findings suggestive of congenital infec-
tion (such as intrauterine growth retardation, hydrops
or ascites, hyperechogenic bowel, pleural or pericardial
effusion, hepatosplenomegaly, intrahepatic calcifications, pseu-
domeconium ileus, and central nervous system abnormali-
ties) [26,37].
Prenatal diagnosis provides the best means for diagnosing
fetal infection. The specificity is usually very good (100%) and
the sensitivity depends on:
•the kind of samples used (amniotic fluid > fetal blood);
•the technique used (real-time PCR > viral culture);
•the number of techniques used;
•the timing of the procedure with respect to (i) the onset
of maternal infection, there is a 6–8-week window
between maternal infection and antenatal procedure
[26,37], and (ii) the gestational age, false-negative results
are common when amniocentesis is carried out before
week 20 of gestation [38]. Little virus is shed by the fetal
kidney because of limited diuresis early on.
Amniocentesis
The amniotic fluid (AF) is the most appropriate material for
the diagnosis of fetal CMV infection. The risk of CMV trans-
mission during antenatal diagnostic procedures performed in
Serological
screening
Negative
IgGIgG– IgM–
Positive
6–12 weeks
of gestation
Hygiene and behaviour measures
Periodic serological testing
IIgG+ IgM–IgG+ IgM+ or
NO
IgG– IgM+
Ad dAd d
Pa s t
infection
Bf 16 k Bf 16 k No
seroconversion
Seroconversion
Advanced
serological testing
Before 16 weeks
of gestation
Serological screening at
35–37 weeks of gestation
*
No further
investigation
Primary
infection
No furtherUltrasonographic
Recommendations
for future pregnancy
No
seroconversion
*
Non primary
infection
Past
infection
Positi ePositi e Negati eNegati e
investigationevaluation
Prenatal
diagnosis
20–21 weeks
of gestation
Positive Negative
Fetal infection
PPV: 100%
No fetal infection
NPV: ~95%
FIG. 1.Recommendations for management of cytomegalovirus (CMV) infection during pregnancy. *Represents, the serological screening at
35–37 weeks of gestation.
s
Represents, the recommendations for future pregnancy. NPV, negative predictive value; PPV, positive predictive
value.
1290Clinical Microbiology and Infection, Volume 17 Number 9, September 2011 CMI
ª2011 The Authors
Clinical Microbiology and Infectionª2011 European Society of Clinical Microbiology and Infectious Diseases,CMI,17, 1285–1293

7. the presence of maternal DNAemia does not seem to be
major as maternal CMV DNAemia is not a significant risk
factor for iatrogenic CMV transmission to the fetus during
amniocentesis [39].
The AF is subjected to a direct search for CMV in culture
and for the viral genome by real-time PCR. If both tech-
niques are negative then fetal infection can be ruled out with
a high degree of certainty (specificity = 100% and negative
predictive value = 94.2%). Positive results in AF identify
CMV-infected fetuses (positive predictive value = 100%) but
do not discriminate those infants who will have symptoms at
birth [40].
If results are positive, investigation of AF is completed by
CMV-DNA load evaluation. Low viral load in AF is consis-
tently found to be associated with asymptomatic congenital
infection. The presence of viral loads <10
3
copies/mL in the
AF, sampled at the appropriate times (at 20–21 weeks of
gestation and when the time interval between onset of
maternal infection is‡6–8 weeks) are a good indicator that
rules out fetal damage at birth and subsequent exacerbation
of infection with the onset of sequelae like hearing loss and
delayed psychomotor development [40].
Although the highest median values of CMV-DNA in AF
tend to indicate an increased risk of severe infection, high
viral loads may be associated with symptomatic or asymp-
tomatic congenital infections indeed, a correlation between
the high CMV load in AF and fetal/neonatal outcome has not
been demonstrated [40].
Cordocentesis
A PCR on fetal blood taken at 20–21 weeks gestation has a
sensitivity for congenital infection lower than that obtained
with AF (sensitivity range, 41–92.3% and specificity about
100%) [18,26]. Studies of prenatal diagnosis of fetal CMV
infection found that no assay for detection of virus or virus
components in fetal blood was sensitive enough to signifi-
cantly improve prenatal diagnosis of intrauterine transmission
of the virus. The sensitivity of PCR on fetal blood reaches
100% when the fetal blood is taken after 30 weeks of gesta-
tion [36].
The sensitivity of specific IgM detection in fetal blood
obtained after 20 weeks of gestation ranged from 55.5%
to 80%. Moreover, past studies demonstrated that the
presence of CMV-specific IgM at significant levels repre-
sented a prognostic marker of congenital CMV disease
[18,26].
More recently, other studies have evoked the prognostic
value of fetal viraemia/viral load and level of specific IgM but
this remains controversial. It has been proposed that platelet
count gives a better indication [36,41].
New data demonstrated that the determination of multi-
ple markers (haematological, biochemical and virological
markers) in fetal blood following virus detection in AF, is
predictive of perinatal outcome in fetuses with CMV infec-
tion [42]. Further studies in a larger number of symptom-
atic cases should be performed to verify the prognostic
efficacy of determination of multiple parameters in fetal
blood.
Diagnosis of Infection in Newborns
At birth, it is essential to use appropriate tests for the diag-
nosis of CMV congenital infection. The standard for the diag-
nosis of congenital CMV infection in newborns remains viral
isolation in the urine or saliva within the first 2 weeks of life
(Fig. 2). But even urinary real-time PCR is a reliable, rapid
andconvenient
method to diagnose congenital CMV infec-
tion.
Detection of specific IgM in neonatal serum also discloses
congenital infection, but IgM antibodies are only present in
between 20 and 70% of infected babies [18].
All infected babies undergo follow-up monitoring at 1, 3, 6
and 12 months of life and annually thereafter until school age
(Fig. 3).
Conclusion
Cytomegalovirus remains the main infectious cause of con-
genital abnormalities in the central nervous system caused by
intrauterine infection in humans, with an average incidence
of approximately 1% of live births.
Although the diagnosis of congenital CMV infection is still
complex, major goals have been achieved in recent years
including: more reliable IgM tests for screening pregnant
women whose pre-pregnancy serological status for CMV is
Virus isolation from urine and/or saliva
in the first 2 weeks of life
Negative
result
Positive
result
Newborn with CMV
congenital infection
Uninfected
newborn
Asymptomatic Symptomatic
No further testing is
required
Therapy IF
neurologic involvement
and/or abnormal
sensorineural findings
Long-term follow-up
(neurodevelopmental,
ophthalmologic, and audiologic evaluation)
FIG. 2.Diagnosis of cytomegalovirus (CMV) infection in newborn.
CMI Lazzarottoet al.CMV infection in pregnancy 1291
ª2011 The Authors
Clinical Microbiology and Infectionª2011 European Society of Clinical Microbiology and Infectious Diseases,CMI,17, 1285–1293

8. unknown; tests to determine the avidity index of anti-CMV
IgG, allowing the diagnosis of a primary CMV infection; and
innovative virological tests to detect the virus in amniotic
fluid.
A fully standardized diagnostic algorithm should lessen the
anxiety felt by pregnant women largely as the result of con-
cerns about mis-management. It was recently demonstrated
that a correct interpretation of serological and virological
tests followed by appropriate counselling by an expert
physician is an effective tool in reducing the number of
unnecessary pregnancy terminations by over 70% [18].
Despite ongoing research, no vaccine is currently available
for use before conception to prevent congenital CMV infec-
tion. Prevention must therefore be based on correct hygiene
and behaviour. Preventive administration of immunoglobulins
or antiviral drugs to pregnant women with primary CMV
infection may reduce the rate of vertical transmission and
improve neonatal outcome, but these findings await confir-
mation in randomized studies on large patient cohorts.
Acknowledgements
Anne Collins edited the English text. This work was sup-
ported by grants from St. Orsola-Malpighi General Hospital
of Bologna (SA43GABR).
Transparency Declaration
The authors declare no potential conflicts of interest.
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