Not immune | Early Acute phase | Acute phase or primary infection | Chronic phase or Reactivation of latent infection or Reinfection (or non-primary infection) | ||
---|---|---|---|---|---|
Description | No symptoms | Flu-like symptoms or asymptomatic | Flu-like symptoms or asymptomatic | ||
CMV IgM | - | + | + | + | - |
CMV IgG | - | - | + | + | + |
CMV IgG Avidity* | n.a. | Low | Low | High | n.a./High |
* A low-avidity anti-CMV IgG detected before the 16th – 18th week of pregnancy, together with a positive anti-CMV IgM, is strong evidence of a recent primary infection, whereas a high avidity index during the first 12 – 16 weeks would be considered a good indicator of past infection. A high avidity result later in gestation cannot rule out a primary infection at an earlier stage of the pregnancy.
n.a. not applicable
Adapted from Revello MG, Gerna G. (2002) Diagnosis and management of human cytomegalovirus infection in the mother, fetus, and newborn infant. Clin Microbiol Rev. 15(4):680-715. doi: 10.1128/CMR.15.4.680-715.2002.
Adapted from:
a) for use on the cobas® e 411 analyzer and the cobas® e 601 / 602 modules
b) for use on the cobas® e 402 and cobas® e 801 analytical units
c) for use on the cobas® 4800 System
d) for use on the cobas® 6800/8800 Systems
CMV IgM | CMV IgG | CMV IgG Avidity | CMV DNA | Interpretation |
---|---|---|---|---|
1st sample | ||||
- | - | N/A | N/A | Patient is not immune and susceptible to infection. Pregnant women should take preventive measures and be closely monitored during pregnancy. |
- | + | N/A | N/A | Infection at least one year previously, and immunity to CMV infection. |
+ | - | N/A | N/A | Very early stage of infection or false positive (unspecific IgM). Perform follow-up test incl. IgG Avidity (when IgG is reactive) after 2 – 3 weeks to confirm either result. |
+ | + | N/A | N/A | |
2nd sample | ||||
+ | + | low | + | Acute infection confirmed. |
+ | + | low | N/A | Acute infection highly suspected – follow-up sample and DNA testing is recommended. |
+ | + | high | N/A or - | Acute infection not confirmed |
* except infants
N/A: not available or not tested
Adapted from:
Pregnant women should take preventive measures and be closely monitored during pregnancy. Follow up until delivery is possible depending on local guidelines. In case very recent infection is suspected, retest a second sample in 2-3 weeks.
Infection occurred at least one year previously.
Immune to CMV infection.
No further testing required.
Continue with serological screening (according to country-specific guidance) and following advices for avoiding infection
Continue with serological screening (according to country-specific guidance) and following advices for avoiding infection
Continue pregnancy monitoring.
Thoroughly evaluate the newborn. Perform postnatal diagnosis.
Discuss options for possible pregnancy outcomes.
Perform CMV IgM and IgG tests
in parallel 2nd sample
Result is implausible.
Investigate for possible analytical errors.
Retrospectively screen with a 1st trimester bood and perform IgG avidity.
Retrospectively screen a 1st trimester blood sample and perform CMV IgG avidity test.
No further testing required if high avidity in first sample (Step 1). High risk of transmission if low avidity in first sample (Step 1).
Test amniotic fluid sample for CMV DNA after 20-21 weeks of gestation and at least 8 weeks after maternal infection.
Consider referring patient to an expert CMV laboratory. Possible additional testing includes maternal viremia assessment (CMV DNA in urine and blood), fetal ultrasounds and MRI, or amniocentesis.
Continue pregnancy monitoring.
Thoroughly evaluate the newborn. Perform postnatal diagnosis.
Discuss options for possible pregnancy outcomes.
Infection occurred at least one year previously.
Immune to CMV infection.
Fetal infection confirmed.
Implausible result.
Possible acute infection or false-positive IgM result.
Test for CMV IgG Avidity.
Implausible result.
Initial results confirmed.
Test for CMV IgG Avidity.
Retrospectively screen a 1st trimester blood sample, and perform CMV IgG avidity test.
Fetal infection not confirmed.